Small area mbsfn enhancement

ABSTRACT

A method, an apparatus, and a computer program product for wireless communication are provided. The apparatus may be a UE. The UE determines whether the UE is located within a sub-region of an MBSFN area based on one or more parameters. The UE receives based on the determination a service over broadcast in the sub-region of the MBSFN area or over unicast outside the sub-region. In an aspect, the MBSFN area may be smaller than a unicast area. In an aspect, adaptive retransmission with a group NACK approach may be used to improve an SNR and reliability.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a national stage entry of PCT Application Serial No.PCT/CN2015/070009, entitled “SMALL MBSFN ENHANCEMENT” and filed on Jan.2, 2015, which claims priority to PCT Application Serial No.PCT/CN2014/070310, entitled “SMALL MBSFN ENHANCEMENT” and filed on Jan.8, 2014, each of which are expressly incorporated by reference herein intheir entirety.

BACKGROUND

1. Field

The present disclosure relates generally to communication systems, andmore particularly, to a Multicast Broadcast Single Frequency Network.

2. Background

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power). Examples of such multiple-access technologies includecode division multiple access (CDMA) systems, time division multipleaccess (TDMA) systems, frequency division multiple access (FDMA)systems, orthogonal frequency division multiple access (OFDMA) systems,single-carrier frequency division multiple access (SC-FDMA) systems, andtime division synchronous code division multiple access (TD-SCDMA)systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example of telecommunicationstandard is Long Term Evolution (LTE). LTE is a set of enhancements tothe Universal Mobile Telecommunications System (UMTS) mobile standardpromulgated by Third Generation Partnership Project (3GPP). LTE isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lowering costs, improving services, making use ofnew spectrum, and better integrating with other open standards usingOFDMA on the downlink (DL), SC-FDMA on the uplink (UL), andmultiple-input multiple-output (MIMO) antenna technology. As usedherein, DL communications may be communications from a network entity(e.g., evolved Node B (eNodeB)) to a user equipment (UE). Further, asused herein, UL communications may be communications from a UE to anetwork entity. However, as the demand for mobile broadband accesscontinues to increase, there exists a need for further improvements inLTE technology. Preferably, these improvements should be applicable toother multi-access technologies and the telecommunication standards thatemploy these technologies.

SUMMARY

In an aspect of the disclosure, a method, a computer program product,and an apparatus are provided. The apparatus may be a UE. The apparatusdetermines whether the apparatus is located within a sub-region of amulticast broadcast single-frequency network (MBSFN) area based on oneor more parameters. The apparatus receives, based on the determination,a service over broadcast when the UE is within the sub-region of theMBSFN area or over unicast when the UE is not within the sub-region. Inan aspect, the MBSFN area is smaller than a unicast area.

In another aspect, the apparatus may be a UE. The apparatus includesmeans for determining whether the UE is located within a sub-region ofan MBSFN area based on one or more parameters. The apparatus includesmeans for receiving based on the determination a service over broadcastwhen the UE is within the sub-region of the MBSFN area or over unicastwhen the UE is not within the sub-region. In an aspect, the MBSFN areais smaller than a unicast area.

In another aspect, the apparatus may be a UE. The apparatus includes amemory and at least one processor coupled to the memory. The at leastone processor is configured to determine whether the apparatus islocated within a sub-region of an MBSFN area based on one or moreparameters, and to receive based on the determination a service overbroadcast when the UE is within the sub-region of the MBSFN area or overunicast when the UE is not within the sub-region. In an aspect, theMBSFN area is smaller than a unicast area.

In another aspect, a computer program product may be provided for a UE.The computer program product includes a computer-readable mediumincluding code for determining whether the UE is located within asub-region of an MBSFN area based on one or more parameters, andreceiving based on the determination a service over broadcast when theUE is within the sub-region of the MBSFN area or over unicast when theUE is not within the sub-region. In an aspect, the MBSFN area is smallerthan a unicast area.

In another aspect of the disclosure, a method, a computer programproduct, and an apparatus are provided. The apparatus may be a basestation. The apparatus provides a service over broadcast to a UE in asub-region of an MBSFN area. The apparatus sends a signal associatedwith one or more parameters to the UE, the signal causing the UE toswitch from reception of the service over broadcast to reception of theservice over unicast. In an aspect, the MBSFN area is smaller than aunicast area.

In another aspect, the apparatus may be a base station. The apparatusincludes means for providing a service over broadcast to a UE in asub-region of an MBSFN area. The apparatus includes means for sending asignal associated with one or more parameters to the UE, the signalcausing the UE to switch from reception of the service over broadcast toreception of the service over unicast. In an aspect, the MBSFN area issmaller than a unicast area.

In another aspect, the apparatus may be a base station. The apparatusincludes a memory and at least one processor coupled to the memory. Theat least one processor is configured to provide a service over broadcastto a UE in a sub-region of an MBSFN area, and to send a signalassociated with one or more parameters to the UE, the signal causing theUE to switch from reception of the service over broadcast to receptionthe service over unicast. In an aspect, the MBSFN area is smaller than aunicast area.

In another aspect, a computer program product may be provided for a basestation. The computer program product includes a computer-readablemedium including code for providing a service over broadcast to a UE ina sub-region of an MBSFN area, and sending a signal associated with oneor more parameters to the UE, the signal causing the UE to switch fromreception of the service over broadcast to reception of the service overunicast. In an aspect, the MBSFN area is smaller than a unicast area.

In another aspect of the disclosure, a method, a computer programproduct, and an apparatus are provided. The apparatus may be a basestation. The apparatus may provide a service over unicast to a UE. Theapparatus may send a signal associated with one or more parameters tothe UE, the signal causing the UE to switch from reception of theservice over unicast to reception of the service over broadcast in asub-region of an MBSFN area. In an aspect, the MBSFN area is smallerthan a unicast area.

In another aspect, the apparatus may be a base station. The apparatusincludes means for providing a service over unicast to a UE. Theapparatus includes means for sending a signal associated with one ormore parameters to the UE, the signal causing the UE to switch fromreception of the service over unicast to reception the service overbroadcast in a sub-region of an MBSFN area. In an aspect, the MBSFN areais smaller than a unicast area.

In another aspect, the apparatus may be a base station. The apparatusincludes a memory and at least one processor coupled to the memory. Theat least one processor is configured to provide a service over unicastto a UE, and to send a signal associated with one or more parameters tothe UE, the signal causing the UE to switch from reception of theservice over unicast to reception of the service over broadcast in asub-region of an MBSFN area. In an aspect, the MBSFN area is smallerthan a unicast area.

In another aspect, a computer program product may be provided for a basestation. The computer program product includes a computer-readablemedium including code for providing a service over unicast to a UE, andsending a signal associated with one or more parameters to the UE, thesignal causing the UE to switch from reception of the service overunicast to reception of the service over broadcast in a sub-region of anMBSFN area. In an aspect, the MBSFN area is smaller than a unicast area.

In another aspect of the disclosure, a method, a computer programproduct, and an apparatus are provided. The apparatus may be a UE. Theapparatus receives, from a base station, a retransmission indicator. Theapparatus receives, from the base station, a broadcast retransmission ofa signal corresponding to the retransmission indicator upon reception ofthe retransmission indicator. The apparatus combines the broadcastretransmission of the signal and an initial transmission of the signalpreviously received by the apparatus to decode the signal.

In another aspect, the apparatus may be a UE. The apparatus includesmeans for receiving, from a base station, a retransmission indicator.The apparatus includes means for receiving, from the base station, abroadcast retransmission of a signal corresponding to the retransmissionindicator upon reception of the retransmission indicator. The apparatusincludes means for combining the broadcast retransmission of the signaland an initial transmission of the signal previously received by theapparatus to decode the signal.

In another aspect, the apparatus may be a UE. The apparatus includes amemory and at least one processor coupled to the memory. The at leastone processor is configured to receive, from a base station, aretransmission indicator, to receive, from the base station, a broadcastretransmission of a signal corresponding to the retransmission indicatorupon reception of the retransmission indicator, and to combine thebroadcast retransmission of the signal and an initial transmission ofthe signal previously received by the apparatus to decode the signal.

In another aspect, a computer program product may be provided for a UE.The computer program product includes a computer-readable mediumincluding code for receiving, from a base station, a retransmissionindicator, receiving from the base station a broadcast retransmission ofa signal corresponding to the retransmission indicator upon reception ofthe retransmission indicator, and combining the broadcast retransmissionof the signal and an initial transmission of the signal previouslyreceived by the UE to decode the signal.

In another aspect of the disclosure, a method, a computer programproduct, and an apparatus are provided. The apparatus may be a basestation. The apparatus sends an initial transmission of a signal to aUE. The apparatus sends a retransmission indicator to the UE. Theapparatus sends a broadcast retransmission of the signal correspondingto the retransmission indicator to the UE after sending theretransmission indicator to facilitate decoding of the signal based on acombination of the broadcast retransmission of the signal and theinitial transmission of the signal.

In another aspect, the apparatus may be a base station. The apparatusincludes means for sending an initial transmission of a signal to a UE.The apparatus includes means for sending a retransmission indicator tothe UE. The apparatus includes means for sending a broadcastretransmission of the signal corresponding to the retransmissionindicator to the UE after sending the retransmission indicator tofacilitate decoding of the signal based on a combination of thebroadcast retransmission of the signal and the initial transmission ofthe signal.

In another aspect, the apparatus may be a base station. The apparatusincludes a memory and at least one processor coupled to the memory. Theat least one processor is configured to send an initial transmission ofa signal to a UE, to send a retransmission indicator to the UE, and tosend a broadcast retransmission of the signal corresponding to theretransmission indicator to the UE after sending the retransmissionindicator to facilitate decoding of the signal based on a combination ofthe broadcast retransmission of the signal and the initial transmissionof the signal.

In another aspect, a computer program product may be provided for a basestation. The computer program product includes a computer-readablemedium including code for sending an initial transmission of a signal toa UE, sending a retransmission indicator to the UE, and sending abroadcast retransmission of the signal corresponding to theretransmission indicator to the UE after sending the retransmissionindicator to facilitate decoding of the signal based on a combination ofthe broadcast retransmission of the signal and the initial transmissionof the signal.

In another aspect of the disclosure, a method, a computer programproduct, and an apparatus are provided. The apparatus may be a UE. Theapparatus receives a serving cell MBMS signal from a serving cell of theapparatus and a neighbor cell MBMS signal from a neighbor cell. Theapparatus determines a degree of synchronization between the servingcell MBMS signal and the neighbor cell MBMS signal. The apparatuscombines the serving cell MBMS signal and the neighbor cell MBMS signalbased on the degree of synchronization.

In another aspect, the apparatus may be a UE. The apparatus includesmeans for receiving a serving cell MBMS signal from a serving cell ofthe apparatus and a neighbor cell MBMS signal from a neighbor cell. Theapparatus includes means for determining a degree of synchronizationbetween the serving cell MBMS signal and the neighbor cell MBMS signal.The apparatus includes means for combining the serving cell MBMS signaland the neighbor cell MBMS signal based on the degree ofsynchronization.

In another aspect, the apparatus may be a UE. The apparatus includes amemory and at least one processor coupled to the memory. The at leastone processor is configured to receive a serving cell MBMS signal from aserving cell of the apparatus and a neighbor cell MBMS signal from aneighbor cell, to determine a degree of synchronization between theserving cell MBMS signal and the neighbor cell MBMS signal, and tocombine the serving cell MBMS signal and the neighbor cell MBMS signalbased on the degree of synchronization.

In another aspect, a computer program product may be provided for a UE.The computer program product includes a computer-readable mediumincluding code for receiving a serving cell MBMS signal from a servingcell of the UE and a neighbor cell MBMS signal from at least oneneighbor cell, determining a degree of synchronization between theserving cell MBMS signal and the neighbor cell MBMS signal, andcombining the serving cell MBMS signal and the neighbor cell MBMS signalbased on the degree of synchronization.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a network architecture.

FIG. 2 is a diagram illustrating an example of an access network.

FIG. 3 is a diagram illustrating an example of a DL frame structure inLTE.

FIG. 4 is a diagram illustrating an example of an UL frame structure inLTE.

FIG. 5 is a diagram illustrating an example of a radio protocolarchitecture for the user and control planes.

FIG. 6 is a diagram illustrating an example of an evolved Node B anduser equipment in an access network.

FIG. 7A is a diagram illustrating an example of an evolved MultimediaBroadcast Multicast Service channel configuration in a MulticastBroadcast Single Frequency Network.

FIG. 7B is a diagram illustrating a format of a Multicast ChannelScheduling Information Media Access Control control element.

FIG. 8A illustrates an example network having a single site MBSFN with asingle MBSFN cell.

FIG. 8B illustrates an example network having a small MBSFN withmultiple MBSFN cells.

FIG. 9 is an example network having a small MBSFN with reduced eMBMScoverage.

FIG. 10A is an example diagram illustrating the first solution of thesecond approach.

FIG. 10B is an example diagram illustrating a first option of the secondapproach's second solution.

FIG. 10C is an example diagram illustrating a second option of thesecond approach's second solution.

FIG. 11 is an example network with multiple MBSFN cells.

FIG. 12 is a flow chart of a method of wireless communication accordingto a first approach.

FIGS. 13A-13C are flow charts of a method of wireless communicationexpanding from FIG. 12.

FIGS. 14A-14C are flow charts of a method of wireless communicationexpanding from FIG. 12.

FIG. 15 is a flow chart of a method of wireless communication accordingto a first approach.

FIG. 16 is a flow chart of a method of wireless communication accordingto a first approach.

FIG. 17 is a flow chart of a method of wireless communication accordingto a second approach.

FIGS. 18A and 18B are flow charts of a method of wireless communicationexpanding from FIG. 17.

FIG. 19 is a flow chart of a method of wireless communication accordingto a second approach.

FIGS. 20A and 20B are flow charts of a method of wireless communicationexpanding from FIG. 17.

FIG. 21 is a flow chart of a method of wireless communication accordingto a third approach.

FIG. 22 is a conceptual data flow diagram illustrating the data flowbetween different modules/means/components in an exemplary apparatus.

FIG. 23 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

FIG. 24 is a conceptual data flow diagram illustrating the data flowbetween different modules/means/components in an exemplary apparatus.

FIG. 25 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, modules, components,circuits, steps, processes, algorithms, etc. (collectively referred toas “elements”). These elements may be implemented using electronichardware, computer software, or any combination thereof. Whether suchelements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented with a “processing system”that includes one or more processors. Examples of processors includemicroprocessors, microcontrollers, digital signal processors (DSPs),field programmable gate arrays (FPGAs), programmable logic devices(PLDs), state machines, gated logic, discrete hardware circuits, andother suitable hardware configured to perform the various functionalitydescribed throughout this disclosure. One or more processors in theprocessing system may execute software. Software shall be construedbroadly to mean instructions, instruction sets, code, code segments,program code, programs, subprograms, software modules, applications,software applications, software packages, routines, subroutines,objects, executables, threads of execution, procedures, functions, etc.,whether referred to as software, firmware, middleware, microcode,hardware description language, or otherwise.

Accordingly, in one or more exemplary embodiments, the functionsdescribed may be implemented in hardware, software, firmware, or anycombination thereof. If implemented in software, the functions may bestored on or encoded as one or more instructions or code on acomputer-readable medium. Computer-readable media includes computerstorage media. Storage media may be any available media that can beaccessed by a computer. By way of example, and not limitation, suchcomputer-readable media can comprise a random-access memory (RAM), aread-only memory (ROM), an electrically erasable programmable ROM(EEPROM), compact disk ROM (CD-ROM) or other optical disk storage,magnetic disk storage or other magnetic storage devices, or any othermedium that can be used to carry or store desired program code in theform of instructions or data structures and that can be accessed by acomputer. Combinations of the above should also be included within thescope of computer-readable media.

FIG. 1 is a diagram illustrating an LTE network architecture 100. TheLTE network architecture 100 may be referred to as an Evolved PacketSystem (EPS) 100. The EPS 100 may include one or more user equipment(UE) 102, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN)104, an Evolved Packet Core (EPC) 110, and an Operator's InternetProtocol (IP) Services 122. The EPS can interconnect with other accessnetworks, but for simplicity those entities/interfaces are not shown. Asshown, the EPS provides packet-switched services, however, as thoseskilled in the art will readily appreciate, the various conceptspresented throughout this disclosure may be extended to networksproviding circuit-switched services.

The E-UTRAN includes the evolved Node B (eNB) 106 and other eNBs 108,and may include a Multicast Coordination Entity (MCE) 128. The eNB 106provides user and control planes protocol terminations toward the UE102. The eNB 106 may be connected to the other eNBs 108 via a backhaul(e.g., an X2 interface). The MCE 128 allocates time/frequency radioresources for evolved Multimedia Broadcast Multicast Service (MBMS)(eMBMS), and determines the radio configuration (e.g., a modulation andcoding scheme (MCS)) for the eMBMS. The MCE 128 may be a separate entityor part of the eNB 106. The eNB 106 may also be referred to as a basestation, a Node B, an access point, a base transceiver station, a radiobase station, a radio transceiver, a transceiver function, a basicservice set (BSS), an extended service set (ESS), or some other suitableterminology. The eNB 106 provides an access point to the EPC 110 for aUE 102. Examples of UEs 102 include a cellular phone, a smart phone, asession initiation protocol (SIP) phone, a laptop, a personal digitalassistant (PDA), a satellite radio, a global positioning system, amultimedia device, a video device, a digital audio player (e.g., MP3player), a camera, a game console, a tablet, or any other similarfunctioning device. The UE 102 may also be referred to by those skilledin the art as a mobile station, a subscriber station, a mobile unit, asubscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or some other suitable terminology.

The eNB 106 is connected to the EPC 110. The EPC 110 may include aMobility Management Entity (MME) 112, a Home Subscriber Server (HSS)120, other MMEs 114, a Serving Gateway 116, a Multimedia BroadcastMulticast Service (MBMS) Gateway 124, a Broadcast Multicast ServiceCenter (BM-SC) 126, and a Packet Data Network (PDN) Gateway 118. The MME112 is the control node that processes the signaling between the UE 102and the EPC 110. Generally, the MME 112 provides bearer and connectionmanagement. All user IP packets are transferred through the ServingGateway 116, which itself is connected to the PDN Gateway 118. The PDNGateway 118 provides UE IP address allocation as well as otherfunctions. The PDN Gateway 118 and the BM-SC 126 are connected to the IPServices 122. The IP Services 122 may include the Internet, an intranet,an IP Multimedia Subsystem (IMS), a PS Streaming Service (PSS), and/orother IP services. The BM-SC 126 may provide functions for MBMS userservice provisioning and delivery. The BM-SC 126 may serve as an entrypoint for content provider MBMS transmission, may be used to authorizeand initiate MBMS Bearer Services within a PLMN, and may be used toschedule and deliver MBMS transmissions. The MBMS Gateway 124 may beused to distribute MBMS traffic to the eNBs (e.g., 106, 108) belongingto a Multicast Broadcast Single Frequency Network (MBSFN) areabroadcasting a particular service, and may be responsible for sessionmanagement (start/stop) and for collecting eMBMS related charginginformation.

FIG. 2 is a diagram illustrating an example of an access network 200 inan LTE network architecture 100 as shown in FIG. 1. In this example, theaccess network 200 is divided into a number of cellular regions (cells)202. One or more lower power class eNBs 208 may have cellular regions210 that overlap with one or more of the cells 202. The lower powerclass eNB 208 may be a femto cell (e.g., home eNB (HeNB)), pico cell,micro cell, or remote radio head (RRH). The macro eNBs 204 are eachassigned to a respective cell 202 and are configured to provide anaccess point to the EPC 110, in FIG. 1, for all the UEs 206 in the cells202. There is no centralized controller in this example of an accessnetwork 200, but a centralized controller may be used in alternativeconfigurations. The eNBs 204 are responsible for all radio relatedfunctions including radio bearer control, admission control, mobilitycontrol, scheduling, security, and connectivity to the serving gateway116 in FIG. 1. An eNB may support one or multiple (e.g., three) cells(also referred to as a sectors). The term “cell” can refer to thesmallest coverage area of an eNB and/or an eNB subsystem serving aparticular coverage area. Further, the terms “eNB,” “base station,” and“cell” may be used interchangeably herein.

The modulation and multiple access scheme employed by the access network200 may vary depending on the particular telecommunications standardbeing deployed. In LTE applications, OFDM is used on the DL and SC-FDMAis used on the UL to support both frequency division duplex (FDD) andtime division duplex (TDD). As those skilled in the art will readilyappreciate from the detailed description to follow, the various conceptspresented herein are well suited for LTE applications. However, theseconcepts may be readily extended to other telecommunication standardsemploying other modulation and multiple access techniques. By way ofexample, these concepts may be extended to Evolution-Data Optimized(EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interfacestandards promulgated by the 3rd Generation Partnership Project 2(3GPP2) as part of the CDMA2000 family of standards and employs CDMA toprovide broadband Internet access to mobile stations. These concepts mayalso be extended to Universal Terrestrial Radio Access (UTRA) employingWideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA;Global System for Mobile Communications (GSM) employing TDMA; andEvolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSMare described in documents from the 3GPP organization. CDMA2000 and UMBare described in documents from the 3GPP2 organization. The actualwireless communication standard and the multiple access technologyemployed will depend on the specific application and the overall designconstraints imposed on the system.

The eNBs 204 may have multiple antennas supporting MIMO technology. Theuse of MIMO technology enables the eNBs 204 to exploit the spatialdomain to support spatial multiplexing, beamforming, and transmitdiversity. Spatial multiplexing may be used to transmit differentstreams of data simultaneously on the same frequency. The data streamsmay be transmitted to a single UE 206 to increase the data rate or tomultiple UEs 206 to increase the overall system capacity. This isachieved by spatially precoding each data stream (i.e., applying ascaling of an amplitude and a phase) and then transmitting eachspatially precoded stream through multiple transmit antennas on the DL.The spatially precoded data streams arrive at the UE(s) 206 withdifferent spatial signatures, which enables each of the UE(s) 206 torecover the one or more data streams destined for that UE 206. On theUL, each UE 206 transmits a spatially precoded data stream, whichenables the eNB 204 to identify the source of each spatially precodeddata stream.

Spatial multiplexing is generally used when channel conditions are good.When channel conditions are less favorable, beamforming may be used tofocus the transmission energy in one or more directions. This may beachieved by spatially precoding the data for transmission throughmultiple antennas. To achieve good coverage at the edges of the cell, asingle stream beamforming transmission may be used in combination withtransmit diversity.

In the detailed description that follows, various aspects of an accessnetwork will be described with reference to a MIMO system supportingOFDM on the DL. OFDM is a spread-spectrum technique that modulates dataover a number of subcarriers within an OFDM symbol. The subcarriers arespaced apart at precise frequencies. The spacing provides“orthogonality” that enables a receiver to recover the data from thesubcarriers. In the time domain, a guard interval (e.g., cyclic prefix)may be added to each OFDM symbol to combat inter-OFDM-symbolinterference. The UL may use SC-FDMA in the form of a DFT-spread OFDMsignal to compensate for high peak-to-average power ratio (PAPR).

FIG. 3 is a diagram 300 illustrating an example of a DL frame structurein LTE. A frame (10 ms) may be divided into 10 equally sized subframes.Each subframe may include two consecutive time slots. A resource gridmay be used to represent two time slots. The resource grid is dividedinto multiple resource elements. In LTE, for a normal cyclic prefix, aresource block contains 12 consecutive subcarriers in the frequencydomain and 7 consecutive OFDM symbols in the time domain, for a total of84 resource elements. For an extended cyclic prefix, a resource blockcontains 12 consecutive subcarriers in the frequency domain and 6consecutive OFDM symbols in the time domain, for a total of 72 resourceelements. Some of the resource elements, indicated as R 302, 304,include DL reference signals (DL-RS). The DL-RS include Cell-specific RS(CRS) (also sometimes called common RS) 302 and UE-specific RS (UE-RS)304. UE-RS 304 are transmitted on the resource blocks upon which thecorresponding physical DL shared channel (PDSCH) is mapped. The numberof bits carried by each resource element depends on the modulationscheme. Thus, the more resource blocks that a UE receives and the higherthe modulation scheme, the higher the data rate for the UE.

FIG. 4 is a diagram 400 illustrating an example of an UL frame structurein LTE. The available resource blocks for the UL may be partitioned intoa data section and a control section. The control section may be formedat the two edges of the system bandwidth and may have a configurablesize. The resource blocks in the control section may be assigned to UEsfor transmission of control information. The data section may includeall resource blocks not included in the control section. The UL framestructure results in the data section including contiguous subcarriers,which may allow a single UE to be assigned all of the contiguoussubcarriers in the data section.

A UE may be assigned resource blocks 410 a, 410 b in the control sectionto transmit control information to an eNB. The UE may also be assignedresource blocks 420 a, 420 b in the data section to transmit data to theeNB. The UE may transmit control information in a physical UL controlchannel (PUCCH) on the assigned resource blocks in the control section.The UE may transmit data or both data and control information in aphysical UL shared channel (PUSCH) on the assigned resource blocks inthe data section. A UL transmission may span both slots of a subframeand may hop across frequency.

A set of resource blocks may be used to perform initial system accessand achieve UL synchronization in a physical random access channel(PRACH) 430. The PRACH 430 carries a random sequence and cannot carryany UL data/signaling. Each random access preamble occupies a bandwidthcorresponding to six consecutive resource blocks. The starting frequencyis specified by the network. That is, the transmission of the randomaccess preamble is restricted to certain time and frequency resources.There is no frequency hopping for the PRACH. The PRACH attempt iscarried in a single subframe (1 ms) or in a sequence of few contiguoussubframes and a UE can make a single PRACH attempt per frame (10 ms).

FIG. 5 is a diagram 500 illustrating an example of a radio protocolarchitecture for the user and control planes in LTE. The radio protocolarchitecture for the UE and the eNB is shown with three layers: Layer 1,Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer andimplements various physical layer signal processing functions. The L1layer will be referred to herein as the physical layer 506. Layer 2 (L2layer) 508 is above the physical layer 506 and is responsible for thelink between the UE and eNB over the physical layer 506.

In the user plane, the L2 layer 508 includes a media access control(MAC) sublayer 510, a radio link control (RLC) sublayer 512, and apacket data convergence protocol (PDCP) 514 sublayer, which areterminated at the eNB on the network side. Although not shown, the UEmay have several upper layers above the L2 layer 508 including a networklayer (e.g., IP layer) that is terminated at the PDN gateway 118, inFIG. 1, on the network side, and an application layer that is terminatedat the other end of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 514 provides multiplexing between different radiobearers and logical channels. The PDCP sublayer 514 also provides headercompression for upper layer data packets to reduce radio transmissionoverhead, security by ciphering the data packets, and handover supportfor UEs between eNBs. The RLC sublayer 512 provides segmentation andreassembly of upper layer data packets, retransmission of lost datapackets, and reordering of data packets to compensate for out-of-orderreception due to hybrid automatic repeat request (HARQ). The MACsublayer 510 provides multiplexing between logical and transportchannels. The MAC sublayer 510 is also responsible for allocating thevarious radio resources (e.g., resource blocks) in one cell among theUEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNBis substantially the same for the physical layer 506 and the L2 layer508 with the exception that there is no header compression function forthe control plane. The control plane also includes a radio resourcecontrol (RRC) sublayer 516 in Layer 3 (L3 layer). The RRC sublayer 516is responsible for obtaining radio resources (e.g., radio bearers) andfor configuring the lower layers using RRC signaling between the eNB andthe UE.

FIG. 6 is a block diagram of an eNB 610 in communication with a UE 650in an access network. In the DL, upper layer packets from the corenetwork are provided to a controller/processor 675. Thecontroller/processor 675 implements the functionality of the L2 layer.In the DL, the controller/processor 675 provides header compression,ciphering, packet segmentation and reordering, multiplexing betweenlogical and transport channels, and radio resource allocations to the UE650 based on various priority metrics. The controller/processor 675 isalso responsible for HARQ operations, retransmission of lost packets,and signaling to the UE 650.

The transmit (TX) processor 616 implements various signal processingfunctions for the L1 layer (i.e., physical layer). The signal processingfunctions include coding and interleaving to facilitate forward errorcorrection (FEC) at the UE 650 and mapping to signal constellationsbased on various modulation schemes (e.g., binary phase-shift keying(BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying(M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded andmodulated symbols are then split into parallel streams. Each stream isthen mapped to an OFDM subcarrier, multiplexed with a reference signal(e.g., pilot) in the time and/or frequency domain, and then combinedtogether using an Inverse Fast Fourier Transform (IFFT) to produce aphysical channel carrying a time domain OFDM symbol stream. The OFDMstream is spatially precoded to produce multiple spatial streams.Channel estimates from a channel estimator 674 may be used to determinethe coding and modulation scheme, as well as for spatial processing. Thechannel estimate may be derived from a reference signal and/or channelcondition feedback transmitted by the UE 650. Each spatial stream maythen be provided to a different antenna 620 via a separate transmitter618TX. Each transmitter 618TX may modulate an RF carrier with arespective spatial stream for transmission.

At the UE 650, each receiver 654RX receives a signal through itsrespective antenna 652. Each receiver 654RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 656. The RX processor 656 implements various signalprocessing functions of the L1 layer. The RX processor 656 may performspatial processing on the information to recover any spatial streamsdestined for the UE 650. If multiple spatial streams are destined forthe UE 650, they may be combined by the RX processor 656 into a singleOFDM symbol stream. The RX processor 656 then converts the OFDM symbolstream from the time-domain to the frequency domain using a Fast FourierTransform (FFT). The frequency domain signal comprises a separate OFDMsymbol stream for each subcarrier of the OFDM signal. The symbols oneach subcarrier, and the reference signal, are recovered and demodulatedby determining the most likely signal constellation points transmittedby the eNB 610. These soft decisions may be based on channel estimatescomputed by the channel estimator 658. The soft decisions are thendecoded and deinterleaved to recover the data and control signals thatwere originally transmitted by the eNB 610 on the physical channel. Thedata and control signals are then provided to the controller/processor659.

The controller/processor 659 implements the L2 layer. Thecontroller/processor 659 can be associated with a memory 660 that storesprogram codes and data. The memory 660 may be referred to as acomputer-readable medium. In the UL, the controller/processor 659provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the core network. The upper layerpackets are then provided to a data sink 662, which represents all theprotocol layers above the L2 layer. Various control signals may also beprovided to the data sink 662 for L3 processing. Thecontroller/processor 659 is also responsible for error detection usingan acknowledgement (ACK) and/or negative acknowledgement (NACK) protocolto support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets tothe controller/processor 659. The data source 667 represents allprotocol layers above the L2 layer. Similar to the functionalitydescribed in connection with the DL transmission by the eNB 610, thecontroller/processor 659 implements the L2 layer for the user plane andthe control plane by providing header compression, ciphering, packetsegmentation and reordering, and multiplexing between logical andtransport channels based on radio resource allocations by the eNB 610.The controller/processor 659 is also responsible for HARQ operations,retransmission of lost packets, and signaling to the eNB 610.

Channel estimates derived by a channel estimator 658 from a referencesignal or feedback transmitted by the eNB 610 may be used by the TXprocessor 668 to select the appropriate coding and modulation schemes,and to facilitate spatial processing. The spatial streams generated bythe TX processor 668 may be provided to different antenna 652 viaseparate transmitters 654TX. Each transmitter 654TX may modulate an RFcarrier with a respective spatial stream for transmission.

The UL transmission is processed at the eNB 610 in a manner similar tothat described in connection with the receiver function at the UE 650.Each receiver 618RX receives a signal through its respective antenna620. Each receiver 618RX recovers information modulated onto an RFcarrier and provides the information to a RX processor 670. The RXprocessor 670 may implement the L1 layer.

The controller/processor 675 implements the L2 layer. Thecontroller/processor 675 can be associated with a memory 676 that storesprogram codes and data. The memory 676 may be referred to as acomputer-readable medium. In the UL, the controller/processor 675provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the UE 650. Upper layer packets fromthe controller/processor 675 may be provided to the core network. Thecontroller/processor 675 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

FIG. 7A is a diagram 750 illustrating an example of an evolved MBMS(eMBMS) channel configuration in an MBSFN. The eNBs 752 in cells 752′may form a first MBSFN area and the eNBs 754 in cells 754′ may form asecond MBSFN area. The eNBs 752, 754 may each be associated with otherMBSFN areas, for example, up to a total of eight MBSFN areas. A cellwithin an MBSFN area may be designated a reserved cell. Reserved cellsdo not provide multicast/broadcast content, but are time-synchronized tothe cells 752′, 754′ and may have restricted power on MBSFN resources inorder to limit interference to the MBSFN areas. Each eNB in an MBSFNarea synchronously transmits the same eMBMS control information anddata. Each area may support broadcast, multicast, and unicast services.A unicast service is a service intended for a specific user, e.g., avoice call. A multicast service is a service that may be received by agroup of users, e.g., a subscription video service. A broadcast serviceis a service that may be received by all users, e.g., a news broadcast.Referring to FIG. 7A, the first MBSFN area may support a first eMBMSbroadcast service, such as by providing a particular news broadcast toUE 770. The second MBSFN area may support a second eMBMS broadcastservice, such as by providing a different news broadcast to UE 760. EachMBSFN area supports one or more physical multicast channels (PMCH)(e.g., 15 PMCHs). Each PMCH corresponds to a multicast channel (MCH).Each MCH can multiplex a plurality (e.g., 29) of multicast logicalchannels. Each MBSFN area may have one multicast control channel (MCCH).As such, one MCH may multiplex one MCCH and a plurality of multicasttraffic channels (MTCHs) and the remaining MCHs may multiplex aplurality of MTCHs.

A UE can camp on an LTE cell to discover the availability of eMBMSservice access and a corresponding access stratum configuration.Initially, the UE may acquire a system information block (SIB) 13(SIB13). Subsequently, based on the SIB13, the UE may acquire an MBSFNArea Configuration message on an MCCH. Subsequently, based on the MBSFNArea Configuration message, the UE may acquire an MCH schedulinginformation (MSI) MAC control element. The SIB13 may include (1) anMBSFN area identifier of each MBSFN area supported by the cell; (2)information for acquiring the MCCH such as an MCCH repetition period(e.g., 32, 64, . . . , 256 frames), an MCCH offset (e.g., 0, 1, . . . ,10 frames), an MCCH modification period (e.g., 512, 1024 frames), asignaling modulation and coding scheme (MCS), subframe allocationinformation indicating which subframes of the radio frame as indicatedby repetition period and offset can transmit MCCH; and (3) an MCCHchange notification configuration. There is one MBSFN Area Configurationmessage for each MBSFN area. The MBSFN Area Configuration message mayindicate (1) a temporary mobile group identity (TMGI) and an optionalsession identifier of each MTCH identified by a logical channelidentifier within the PMCH, and (2) allocated resources (i.e., radioframes and subframes) for transmitting each PMCH of the MBSFN area andthe allocation period (e.g., 4, 8, . . . , 256 frames) of the allocatedresources for all the PMCHs in the area, and (3) an MCH schedulingperiod (MSP) (e.g., 8, 16, 32, . . . , or 1024 radio frames) over whichthe MSI MAC control element is transmitted.

FIG. 7B is a diagram 790 illustrating the format of an MSI MAC controlelement. The MSI MAC control element may be sent once each MSP. The MSIMAC control element may be sent in the first subframe of each schedulingperiod of the PMCH. The MSI MAC control element can indicate the stopframe and subframe of each MTCH within the PMCH. There may be one MSIper PMCH per MBSFN area.

eNBs in an MBSFN area may be synchronized to enhance signal transmissionwhen signals from the eNBs in the MBSFN area are combined to provide anenhanced signal, especially in an eMBMS. However, it may be difficult tosynchronize eNBs to form an MBSFN area. A small MBSFN such as a singlesite MBSFN may be utilized as an approach that falls between a largeMBSFN and a unicast network. For example, a number of cells in a smallMBSFN may be smaller than a number of cells in a surrounding unicastnetwork, and a single site MBSFN may have a single cell for the MBSFN.The small MBSFN may be used for a group call if all the UEs in the groupare located within the MBSFN area. A group call is communication fromeNBs to the UEs in a group. In such a case, the small MBSFN or thesingle site MBSFN may not be effective in signal transmission exceptwhen the surrounding cells are not transmitting signals.

FIG. 8A illustrates an example network 800 having a single site MBSFNwith a single MBSFN cell. In FIG. 8A, an MBSFN cell 802 forms a smallMBSFN area surrounded by non-MBSFN cells (e.g., unicast cells) 804 thatform a unicast area. The MBSFN eNB 812 is assigned to the MBSFN cell802. Each of non-MBSFN eNBs 814 is assigned to a corresponding non-MBSFNcell 804. In an aspect, the MBSFN may include more than one cell (e.g.,three MBSFN cells), where a number of the MBSFN cells in the small MBSFNis less than a number of surrounding unicast cells. FIG. 8B illustratesan example network 850 having a small MBSFN with multiple MBSFN cells.In FIG. 8B, MBSFN cells 852 form a small MBSFN area surrounded bynon-MBSFN cells (e.g., unicast cells) 854 that form a unicast area. Eachof MBSFN eNBs 862 is assigned to a corresponding MBSFN cell 852. Each ofnon-MBSFN eNBs 864 is assigned to a corresponding non-MBSFN cell 854. Inthe example shown in FIG. 8B, the number of the MBSFN cells 852 is threeand the number of the non-MBSFN cells (e.g., unicast cells) 854 is nine.Thus, the number of MBSFN cells 852 is less than the number of non-MBSFNcells 854.

According to a first approach of the disclosure, reduced eMBMS coveragefor a small MBSFN is used to improve service in the small MBSFN. Inparticular, eMBMS coverage for a small MBSFN may be reduced to asub-region of the small MBSFN, where the sub-region is smaller than anarea covered by the MBSFN. The UE receives the service via eMBMS withinthe sub-region, and receives the service via unicast outside thesub-region. FIG. 9 is an example network 900 having a small MBSFN withreduced eMBMS coverage. For example, the small MBSFN may be defined asan area in which a service may be supported based on a MCS threshold. InFIG. 9, an MBSFN cell 902 forms a small MBSFN area surrounded bynon-MBSFN cells (e.g., unicast cells) 904 (904 a-904 f) that form aunicast area. The eNB 912 is assigned to the MBSFN cell 902, where theeNB 912 may be an MBSFN eNB. eNBs 914 a-914 f are assigned to non-MBSFNcells 904 a-904 f, respectively, where the eNBs 914 a-914 f may benon-MBSFN eNBs. In FIG. 9, the small MBSFN area may provide reducedeMBMS coverage in a sub-region 932 of the MBSFN cell 902. Thus, thesub-region 932 is an MBSFN coverage area that is smaller than the MBSFNarea covered by the MBSFN cell 902. If the UE (e.g., a UE 952) is withinthe sub-region 932, the UE within the sub-region 932 receives theservice over broadcast. If the UE (e.g., a UE 954) is outside thesub-region 932, the UE outside the sub-region 932 receives the serviceover unicast. In the example illustrated in FIG. 9, the sub-region 932is a circular shape with a radius R. It is noted that the shape of thesub-region is not limited to a circle, and may be any shape. Further, itis noted that the small MBSFN may include more than one MBSFN cell.

There may be at least two service continuity scenarios involving thesmall MBSFN with reduced eMBMS coverage. In a first scenario, referredto as a broadcast (BC) to unicast (UC) scenario, the UE moves out of abroadcast coverage area (e.g., an eMBMS coverage area), and thus mayswitch from receiving over BC (e.g., via eMBMS) to receiving over UC. Inone example, if the UE cannot receive the service from the MBSFN (e.g.,at least in part because many cells in the MBSFN cannot besynchronized), then the UE can switch from BC to the UC to receive theservice over unicast. In a second scenario, referred to as a UC to BCscenario, the UE moves into the broadcast coverage area (e.g., eMBMScoverage area) from a unicast coverage area, and thus may switch fromreceiving over UC to receiving over BC (e.g., via eMBMS).

When the UE moves from the MBSFN coverage area to a non-MBSFN coveragearea, the service (e.g., group call) may be switched from BC to UC toensure service continuity (e.g., to receive the service withoutinterruption). For example, referring to the example of FIG. 9, as theUE moves from the sub-region 932 to an area outside of the sub-region932, the UE switches from receiving over BC (e.g., via eMBMS) toreceiving over UC to receive a service (e.g., a group call)continuously. The switching from BC to UC may be based on one or moreparameters, such as signal characteristics associated with the BCservice, signal characteristics associated with the UC service, timingadvance, a location of the UE, path loss, a parameter of the sub-regionof the MBSFN area, and geometry. For example, if the signalcharacteristics associated with the BC service indicates lower BC signalstrength and/or the signal characteristics associated with the UCservice indicates higher UC signal strength, the UE may switch from BCto UC.

In particular, the signal characteristic (BC or UC) may be associatedwith a serving base station and neighboring base stations. For example,the eNB 912 may receive signal characteristics from each of the UEs 952and 954. The eNB 912 may receive signal characteristics from the UE 952based on unicast and/or multicast/broadcast transmissions from the eNBs912, 914 b, and 914 c; and from the UE 954 based on unicast and/ormulticast/broadcast transmissions from the eNBs 912, 914 e, and 914 fThus, for example, the eNB 912 may receive signal characteristics from aUE based on unicast and/or multicast/broadcast transmissions from one ormore eNBs within proximity of the UE. The signal characteristicsassociated with the BC service may include broadcast reference signalreceived power (RSRP), broadcast reference signal received quality(RSRQ), and/or a signal-to-interference-plus-noise ratio (SINR). Thesignal characteristics associated with the UC service may includeunicast RSRP, unicast RSRQ, and/or a channel quality indicator (CQI).The geometry may include information indicating received signal powerfrom the MBSFN cell (e.g., the MBSFN cell 802) in relation to otherinterferences/path loss. Thus, a UE with a high geometry value may havehigh signal power with low interferences/path loss.

In the first scenario, the switching from BC to UC may be performedbased on at least one of three options explained below. According to afirst option of the first scenario, the UE may determine to switch fromBC to UC based on the above parameters (e.g., parameters such as signalcharacteristics associated with the BC service, signal characteristicsassociated with the UC service, timing advance, a location of the UE,path loss, a parameter of the sub-region of the MBSFN area, andgeometry). The UE may switch from BC to UC based on the parameters andthresholds associated with the parameters. For example, if the UEdetermines that the broadcast RSRP is less than a certain threshold,then the UE may switch from BC to UC. According to a second option ofthe first scenario, a network (e.g., an eNB) may provide the UE withthresholds corresponding to the above parameters, such that the UE maydetermine to switch from BC to UC based on the thresholds and the aboveparameters. For example, the eNB may provide the UE with a threshold fora broadcast RSRP, and if the UE determines that the broadcast RSRP isless than the threshold provided by the network, the UE may switch fromBC to UC. Thus, according to the second option of the first scenario,the network assists the UE in determining whether to switch from BC toUC by providing the thresholds. According to a third option of the firstscenario, the network (e.g., an eNB) may send a handover command to theUE based on the above parameters, where the handover command causes theUE to switch from BC to UC. For example, if the eNB 912 determines thatthe broadcast RSRP for the UE 954 is less than a certain threshold, theeNB 912 may send a handover command to the UE 954 to cause the UE 954 toswitch from BC to UC.

In the second scenario, when the UE moves from a non-MBSFN coverage areato the MBSFN coverage area, the UE may determine to switch fromreceiving the service (e.g. group call) over UC to receiving the serviceover BC to ensure service continuity (e.g., receiving the servicewithout interruption). For example, the UE may determine to enter theeMBMS coverage to receive the service over broadcast based on checkingthe SIB13 acquired by the UE. The switching from UC to BC may be basedon one or more parameters, such as signal characteristics associatedwith the BC service, signal characteristics associated with the UCservice, timing advance, a location of the UE, path loss, a parameter ofthe sub-region of the MBSFN area, and geometry. In the second scenario,the switching from UC to BC may be performed according to at least oneof three options explained below.

According to the first option of the second scenario, the UE that isreceiving the service over UC continues to measure one or more MBSFNparameter periodically, and may switch to receiving the service over BCwhen the UE determines that the MBSFN broadcast is available. Thus, theUE continues to measure the one or more MBSFN parameters periodicallyeven when the UE is using the UC bearer. For example, while the UE 954receives the service over UC via the eNB 914 c, the UE 954 continues tomeasure the MBSFN signal strength from the eNB 912, and may switch toreceiving the service over BC if the MBSFN signal strength from the eNB912 is strong (e.g., greater than a certain threshold). According to thesecond option of the second scenario, an eNB provides the UE withthresholds corresponding to the above parameters, and the UE determinesto switch from UC to BC based on the thresholds and the aboveparameters. If the UE determines that the broadcast signal does notsatisfy a condition based on the thresholds provided by the eNB, thenthe UE may determine to switch from receiving the service over UC toreceiving the service over BC. For example, the eNB may provide the UEwith a threshold for a unicast RSRP, and if the UE determines that theunicast RSRP is less than the threshold provided by the eNB, the UE mayswitch from UC to BC. According to a third option of the secondscenario, an eNB sends a command to the UE to redirect from UC to BCbased on UE's unicast measurement and optionally MBSFN (broadcast)measurement. For example, the unicast measurement and the MBSFNmeasurement may be measurements of unicast signal strength and MBSFNsignal strength, respectively. The unicast measurement and the MBSFNmeasurement are performed by the UE and are sent to the eNB. Thus,according to the UE's unicast measurement and/or MBSFN measurement, theeNB may determine that the broadcast signal is stronger than the unicastsignal, and consequently determine to send a command to the UE to switchfrom UC to BC. For example, if the UE initially receives the serviceover unicast via the eNB 914 c and the eNB 914 c determines that theunicast RSRP for the UE 954 is less than a certain threshold, the eNB914 c may send a command to the UE 954 to cause the UE 954 to switchfrom UC to BC.

According to a second approach, after the eNB initially transmits asignal to the UE, the eNB may retransmit the signal to improve overallsignal quality of an eMBMS. After the eNB initially transmits abroadcast signal (e.g., an eMBMS signal), the eNB may send the UE anindicator of a broadcast retransmission of the signal. The broadcastretransmission indicator indicates to the UE that a signal to be sent tothe UE is a retransmission of the signal. Thus, the retransmissionindicator may differentiate the initial transmission and theretransmission of the signal. The broadcast retransmission indicator maybe sent via MCCH or MSI or dedicated signaling. After transmitting thebroadcast retransmission indicator, the eNB retransmits the broadcastsignal to the UE. The eNB may retransmit the broadcast signal in thesame MSP as an MSP of an initially transmitted eMBMS signal or in adifferent MSP. The UE combines multiple transmissions (e.g., thebroadcast retransmission and the initial transmission) to generate thebroadcast signal, in order to improve the signal quality. The eNB mayuse a normal CP (e.g., 5 μs) instead of an extended CP (e.g., 16.6 μs).It is noted that the eNB may retransmit the signal more than once. Thus,the UE may combine multiple retransmissions of the signal with theinitial transmission of the signal to generate the broadcast signal. Insuch a case, before each of the multiple retransmissions of the signal,the eNB may send a broadcast retransmission indicator corresponding toeach of the multiple retransmissions of the signal to the UE.

According to a first solution of the second approach, the eNB performsfixed retransmission based on signal quality of the MBSFN area. Thesignal quality of the MBSFN area may be known to the network. Inparticular, based on a signal quality (e.g., an SNR) of the MBSFN areaand an MCS, an MCE informs the eNB to repeat transmission(retransmission) of packets of the signal one or more times. Forexample, if the SNR is low (e.g., below a certain threshold), then theMCE may prompt the eNB to retransmit the signal one or more times. TheUE receives a retransmission of the signal, and combines theretransmission of the signal with the initial transmission of the signalto decode the signal. The eNB may perform multiple retransmissions ofthe signal after the initial transmission. In such a case, the eNB sendsa broadcast retransmission indicator corresponding to each of themultiple retransmissions of the signal to the UE before each of themultiple retransmissions of the signal. After receiving the multipleretransmissions of the signal, the UE may combine the initialtransmission of the signal and the multiple retransmissions of thesignal. If the eNB performs multiple retransmissions of the signal, theeNB may bundle the multiple retransmissions of the signal, and transmitthe bundle of the multiple retransmissions to the UE.

FIG. 10A is an example diagram 1000 illustrating the first solution ofthe second approach. The example diagram 1000 includes a UE 1002, an eNB1004, and an MCE 1006. The eNB 1004 sends 1012 an initial transmissionof a signal to the UE 1002. When the MCE 1006 determines 1014 that anSNR of an MBSFN area associated with the eNB 1004 is low, the MCEprompts 1016 the eNB 1004 to send a retransmission of the signal to theUE 1002. Subsequently, the eNB 1004 sends 1018 a retransmissionindicator to the UE 1002, and then sends 1020 a retransmission of thesignal to the UE 1002. The UE 1002 combines 1022 the initialtransmission of the signal and the retransmission of the signal todecode the signal.

A second solution of the second approach utilizes adaptiveretransmission based on feedback from a UE. If the MCE determines basedon the feedback from UEs that some UEs did not successfully receive aninitial transmission of a broadcast signal from an eNB, then the MCE orthe eNB may determine to perform retransmission of the signal. Thefeedback from the UE may be based on a group NACK approach. According tothe group NACK approach, if the UE determines that packet(s) of aninitial transmission signal from an eNB cannot be decoded, then the UEsends a NACK via a common resource. The common resource is shared amongthe UEs within the same group such that the UEs in the same group maysend a NACK to the eNB via the common resource. The eNB may decide howmany UEs did not receive the transmission based on the power of thesignal strength of a NACK received via the common source. Based on thepower of the signal strength of NACK from a group of the UEs, the eNBmay be configured for the group of the UEs. The eNB may also beconfigured for the group of the UEs based on the power of signalstrength of ACK from the group of the UEs.

According to a first option of the second approach's second solution,retransmission of the signal is performed based on the MBSFNmeasurements. A common NACK resource is assigned for the UEs in the samegroup and is shared by the UEs in the same group. An eNB may sendinformation on the common NACK resource to each of the UEs in the samegroup that are served by (e.g., camped on) the eNB. In one example, theUEs in the same group may be served by multiple eNBs. The information onthe common NACK resource may be sent to the UEs via a SIB 13 or an MCCHor dedicated signaling. When a UE fails to decode packets of the signalof an initial transmission, the UE sends a NACK to the eNB via thecommon NACK resource. Each eNB of the MBSFN reports a received energymetric of a NACK to an MCE. Based on the energy metric of the NACK, theMCE decides whether to prompt the eNB to re-transmit the packets of thesignal to the UE. For example, the MCE may estimate how many UEs in thesame group did not receive the initial transmission from the eNB basedon the energy metric of NACK, and may determine whether to prompt theeNB to perform retransmission based on the estimation. In an aspect, theMCE may decide to prompt the one or more eNBs to retransmit the packetsbased on a signal report such as the RSSI reports. For example, the MCEmay decide to prompt the one or more eNBs to retransmit the packet if anRSSI in the RSSI report is less than a certain threshold. The MCE maydecide to prompt retransmission on all of the cells in the MBSFN or on asubset of the cells in the MBSFN. The eNB may send a retransmissionindicator to the UE to inform that the signal being sent to the UE isretransmission. The indication of retransmission may be a new dataindicator (NDI). After sending the retransmission indicator to the UE,the eNB sends retransmission of the signal to the UE. The eNB mayperform retransmission of the signal to the UE on a next MSP. When theUE receives a retransmitted signal, the UE combines the retransmittedsignal with an initially transmitted signal.

FIG. 10B is an example diagram 1030 illustrating a first option of thesecond approach's second solution. The example diagram 1030 includes UEs1032 a-1032 c in a same group, an eNB 1034, and an MCE 1036. The eNB1034 sends 1042 information on a common NACK resource to the UE 1032 a.The eNB 1034 may send information on the common NACK resource to the UEs1032 b and 1032 c. The eNB 1034 sends 1044 an initial transmission of asignal to the UE 1032 a. The common NACK resource is shared by the UEs1032 a-1032 c in the same group. When the UE 1032 a determines 1046 thatUE 1032 a fails to decode the signal successfully, the UE 1032 a sends1048 a NACK to the eNB 1034 via the common NACK resource. The UEs 1032 band 1032 c may also send a NACK to the eNB 1034 via the common NACKresource upon failing to successfully decode the signal. The eNB 1034reports 1050 an energy metric of the received NACK to the MCE 1036. Whenthe MCE 1036 determines 1052 to retransmit the signal based on theenergy metric, the MCE 1036 prompts 1054 the eNB 1034 to send aretransmission of the signal to the UE 1032 a. Subsequently, the eNB1034 sends 1056 a retransmission indicator to the UE 1032 a, and thensends 1058 a retransmission of the signal to the UE 1032 a. The UE 1032a combines 1060 the initial transmission of the signal and theretransmission of the signal to decode the signal.

According to a second option of the second approach's second solution,retransmission of the signal is performed based on a cell. The commonNACK resource is configured per cell, or per group per cell. It is notedthat the common NACK resource is configured per group per cell whenmultiple common NACK resources are configured for each cell. The commonNACK resource is assigned for the UEs in the same group that are servedby (e.g., camped on) the eNB and is shared by the UEs in the same group.In one example, the UEs in the same group may be served by multipleeNBs. An eNB sends the configured common NACK resource and a group radionetwork temporary identifier (G-RNTI) to a UE. The common NACK resourceand the G-RNTI may be sent to the UE via a SIB13. Each TMGI may beassigned with multiple pairs of a G-RNTI and a NACK resource in a cell.When the UE fails to decode packets of the signal of an initialtransmission, the UE sends a NACK to an eNB via the configured commonNACK resource. The eNB determines whether to retransmit a signal to theUE based on the received energy metric of the NACK. For example, the eNBmay determine whether to retransmit the signal to the UE if the receivedenergy metric of the NACK is less than a certain threshold. If the eNBdetermines to retransmit the signal, the eNB sends a retransmissionindicator to the UE. Subsequently, the eNB schedules a transmissionaddressed by G-RNTI for the retransmission of the signal, and thenperforms the retransmission of the signal to the UE based on schedulingon the G-RNTI. When the UE receives the retransmitted signal, the UEcombines the retransmitted signal with the initially transmitted signal.

FIG. 10C is an example diagram 1070 illustrating a second option of thesecond approach's second solution. The example diagram 1070 includes UEs1072 a-1072 c in a same group and an eNB. The eNB 1074 sends 1082information on a common NACK resource and a G-RNTI to the UE 1072 a. TheeNB 1074 may send information on the common NACK resource to the UEs1072 b and 1072 c. The eNB 1074 sends 1084 an initial transmission of asignal to the UE 1072 a. When the UE 1072 determines 1086 that thesignal is not successfully decoded, the UE 1072 a sends 1088 a NACK tothe eNB 1074 via the common NACK resource. When the eNB 1074 determines1090 to retransmit the signal based on the energy metric of the NACK,the eNB 1074 sends 1092 a retransmission indicator to the UE 1072 a, andthen sends 1094 a retransmission of the signal to the UE 1072 a. The UE1072 a combines 1096 the initial transmission and the retransmission ofthe signal to decode the signal.

According to a third approach, the UE receives MBMS signals frommultiple cells that are not synchronized and combines the receivedsignals even if the cells are not synchronized. Depending on a degree ofsynchronization, two different scenarios may be treated differently.FIG. 11 is an example network 1100 with multiple MBSFN cells. MBSFN eNBs1112 a-1112 c are assigned to MBSFN cells 1102 a-1102 c, respectively.Each of non-MBSFN eNBs 1114 is assigned to a corresponding non-MBSFNcell 1104. For a UE 1152 in the MBSFN cell 1102, the serving cell is theMBSFN cell 1102 a, and neighbor cells are MBSFN cells 1112 b and 1112 c.The UE 1152 receives signals from the serving cell and the neighborcells. The neighbor cells may be adjacent to the serving cell. In afirst scenario, the signal from the serving cell and the signals fromthe neighbor cells are loosely synchronized. In a second scenario, thesignal from the serving cell and the signals from the neighbor cells areasynchronous. In one example, if the UE determines that a degree ofsynchronization of the serving cell signal and a neighbor cell signal isgreater than or equal to a threshold, the UE may determine that theserving cell and the neighbor cell are at least loosely synchronized. Onthe contrary, if the UE determines that the degree of synchronization ofthe serving cell signal and a neighbor cell signal is less than thethreshold, the UE may determine that the serving cell and the neighborcell are asynchronous. It is noted that for a UE that is capable ofcarrier aggregation (CA), the UE may use another radio chain to listento other cells.

In a first scenario where the serving cell and the neighbor cell areloosely synchronized, the UE buffers for a timing difference between aserving cell MBMS signal and a neighbor cell MBMS signal. The UE maybuffer for the timing difference by buffering log-likelihood ratios(LLRs) for the timing difference. In particular, when the serving celland the neighbor cell are loosely synchronized, the UE may not bufferthe entire subframe, but instead may buffer for the timing difference tocombine the signals based on the timing difference. Because the UE maybuffer only for the timing difference (not for the entire subframe), thememory requirement for the buffering is low. For example, if thesynchronization error is small (e.g., a half symbol or around 30 microseconds), the buffer according to the first scenario needs to hold only35 micro seconds of data. In this example, the synchronization error of35 micro seconds is small compared to one subframe (1 ms), but largeenough to be more than a CP so that the signals may not combine directlyover the air. The UE may buffer multiple timing differences between theserving cell MBMS signal and multiple neighbor cell MBMS signals, suchthat the serving cell MBMS signal and multiple neighbor cell MBMSsignals may be synchronized.

In a second scenario where the serving cell and the neighbor cell areasynchronous, the UE buffers the entire subframe of each signal, andthen combines the signals. The UE is configured to measure the frameoffsets between the signals before buffering.

FIG. 12 is a flow chart 1200 of a method of wireless communicationaccording to a first approach. The method may be performed by a UE. At1202, the UE determines whether the UE is located within a sub-region ofan MBSFN area based on one or more parameters. At 1204, the UE receives,based on the determination at 1202, a service over broadcast when the UEis located within the sub-region of the MBSFN area or over unicast whenthe UE is not located within the sub-region. In an aspect, the MBSFNarea is smaller than a unicast area. In an aspect, the one or moreparameters may include a characteristic associated with a broadcastservice, a characteristic associated with a unicast service, a timingadvance value, a location of the UE, a path loss value, a parameter ofthe sub-region of the MBSFN area, a geometry, or any combinationthereof. For example, referring back to FIG. 9, the small MBSFN area mayprovide reduced eMBMS coverage in a sub-region 932 of the MBSFN cell902, where the sub-region 932 is smaller than an MBSFN area covered bythe MBSFN cell 902. For example, referring back to FIG. 9, the UEreceives the service over broadcast if the UE (e.g., a UE 952) is withinthe sub-region 932, and the UE receives the service over unicast if theUE (e.g., a UE 954) is outside the sub-region 932. As discussed supra,for example, a number of cells in a small MBSFN may be smaller than anumber of cells in a surrounding unicast network.

FIG. 13A is a flow chart 1300 of a method of wireless communicationexpanding from FIG. 12. The method may be performed by a UE, where theUE initially receives the service over broadcast. At 1302, the UEswitches from reception of the service over broadcast to reception ofthe service over unicast based on the one or more parameters. Forexample, as discussed supra, the UE may determine to switch from BC toUC based on parameters such as a characteristic associated with abroadcast service, a characteristic associated with a unicast service, atiming advance value, a location of the UE, a path loss value, aparameter of the sub-region of the MBSFN area, and a geometry.

FIG. 13B is a flow chart 1330 of a method of wireless communicationexpanding from FIG. 12. At 1332, the UE receives, from a base station,one or more thresholds associated with the one or more parameters. At1334, the UE switches between reception of the service over broadcastand reception of the service over unicast based on the one or morethresholds and the one or more parameters. In one aspect, for example,as discussed supra, an eNB may provide the UE with thresholdscorresponding to the parameters, such that the UE may determine toswitch from BC to UC based on the thresholds and the parameters. Forexample, as discussed supra, the eNB may provide the UE with a thresholdfor a broadcast RSRP, and if the UE determines that the broadcast RSRPis less than the threshold provided by the network, the UE may switchfrom BC to UC. In another aspect, for example, as discussed supra, aneNB provides the UE with thresholds corresponding to the aboveparameters, and the UE determines to switch from UC to BC based on thethresholds and the above parameters. For example, as discussed supra, ifthe UE determines that the broadcast signal does not satisfy a conditionbased on the thresholds provided by the eNB, then the UE may determineto switch from receiving the service over UC to receiving the serviceover BC.

FIG. 13C is a flow chart 1350 of a method of wireless communicationexpanding from FIG. 12. The method may be performed by a UE, where theUE initially receives the service over broadcast. At 1352, the UEreceives a handover command from a base station, where the handovercommand is generated by the base station based on the one or moreparameters. At 1354, the UE switches from reception of the service overbroadcast to reception of the service over unicast based on the handovercommand. For example, as discussed supra, the network may send ahandover command to the UE based on the parameters, where the handovercommand causes the UE to switch from BC to UC. For example, as discussedsupra, if the eNB 912 determines that the broadcast RSRP for the UE 954is less than a certain threshold, the eNB 912 may send a handovercommand to the UE 954 to cause the UE 954 to switch from BC to UC.

FIG. 14A is a flow chart 1400 of a method of wireless communicationexpanding from FIG. 12. The method may be performed by a UE, where theUE initially receives the service over unicast. At 1402, the UE measuresignal quality from the MBSFN area. At 1404, the UE switches fromreceiving the service over unicast to receiving the service overbroadcast based on the measured signal quality. For example, asdiscussed supra, the UE that is receiving the service over UC continuesto measure the MBSFN periodically, and may switch to receiving theservice over BC when the UE determines that MBSFN broadcast isavailable. For example, referring back to FIG. 9, while the UE 954receives the service over UC via the eNB 914 c, the UE 954 continues tomeasure the MBSFN signal strength from the eNB 912, and may switch toreceiving the service over BC if the MBSFN signal strength from the eNB912 is strong.

FIG. 14C is a flow chart 1450 of a method of wireless communicationexpanding from FIG. 12. The method may be performed by a UE, where theUE initially receives the service over unicast. At 1452, the UE performsa unicast measurement of the UE, an MBSFN measurement, or anycombination thereof. At 1454, the UE transmits the unicast measurementof the UE, the MBSFN measurement, or a combination thereof to a basestation. At 1456, the UE receives a command from the base station toswitch from receiving the service over unicast to receiving the serviceover broadcast based on the transmission. At 1458, the UE switches fromreception of the service over unicast to reception of the service overbroadcast based on the command. For example, as discussed supra, an eNBsends a handover command to the UE to redirect from UC to BC based onUE's unicast measurement and optionally MBSFN (broadcast) measurement.The unicast measurement and the MBSFN measurement are performed by theUE and are sent to the eNB. Referring back to FIG. 9, for example, ifthe UE initially receives the service over unicast via the eNB 914 c andthe eNB 914 c determines that the unicast RSRP for the UE 954 is lessthan a certain threshold, the eNB 914 c may send a command to the UE 954to cause the UE 954 to switch from UC to BC.

FIG. 15 is a flow chart 1500 of a method of wireless communicationaccording to a first approach. The method may be performed by a basestation. At 1502, the base station provides a service over broadcast toa UE in a sub-region of an MBSFN area. At 1504, the base station sends asignal associated with one or more parameters to the UE, the signalcausing the UE to switch from receiving the service over broadcast toreceiving the service over unicast. In an aspect, the MBSFN area issmaller than a unicast area. Referring back to FIG. 9, for example, asthe UE moves from the sub-region 932 to an outside of the sub-region932, the UE switches from receiving over BC (e.g., via eMBMS) toreceiving over UC to receive a service (e.g., a group call)continuously, where the switching from BC to UC may be based on one ormore parameters and other information received from the base station. Asdiscussed supra, for example, a number of cells in a small MBSFN may besmaller than a number of cells in a surrounding unicast network.

In an aspect, the one or more parameters may include a characteristicassociated with a broadcast service, a characteristic associated with aunicast service, a timing advance value, a location of the UE, a pathloss value, a parameter of the sub-region of the MBSFN area, and ageometry. In an aspect, the signal may include one or more thresholdsfor the one or more parameters, the one or more thresholds for the oneor more parameters causing the UE to switch from receiving the serviceover broadcast to receiving the service over unicast. As discussedsupra, an eNB provides the UE with thresholds corresponding to the aboveparameters, such that the UE may determine to switch from BC to UC basedon the thresholds and the above parameters. In an aspect, the basestation may determine to send a handover command in the signal to the UEbased on the one or more parameters, and the handover command causes theUE to switch from receiving the service over broadcast to receiving theservice over unicast. As discussed supra, an eNB sends a handovercommand to the UE based on the above parameters, where the handovercommand causes the UE to switch from BC to UC.

FIG. 16 is a flow chart 1600 of a method of wireless communicationaccording to a first approach. The method may be performed by a basestation. At 1602, the base station provides a service over unicast to aUE. At 1604, the base station sends a signal associated with one or moreparameters to the UE, the signal causing the UE to switch from receivingthe service over unicast to receiving the service over broadcast in asub-region of an MBSFN area. In an aspect, the MBSFN area is smallerthan a unicast area. As discussed supra, when the UE moves from anon-MBSFN coverage area to the MBSFN coverage area, the UE may determineto switch from receiving the service (e.g. group call) over UC toreceiving the service over BC to ensure service continuity, where theswitching from UC to BC may be based on one or more parameters and otherinformation received from the base station.

In an aspect, the one or more parameters may include a characteristicassociated with a broadcast service, a characteristic associated with aunicast service, a timing advance value, a location of the UE, a pathloss value, a parameter of the sub-region of the MBSFN area, and ageometry. In an aspect, the signal may include one or more thresholdsfor the one or more parameters, the one or more thresholds for the oneor more parameters causing the UE to switch from receiving the serviceover unicast to receiving the service over broadcast. As discussedsupra, an eNB provides the UE with thresholds corresponding to the aboveparameters, and the UE determines to switch from UC to BC based on thethresholds and the above parameters. In an aspect, the base station maydetermine to send a command in the signal to the UE based on the one ormore parameters, and the command causes the UE to switch from receivingthe service over unicast to receiving the service over broadcast, thecommand being based on a unicast measurement of the UE, an MBSFNmeasurement, or any combination thereof. As discussed supra, an eNBsends a command to the UE to redirect from UC to BC based on UE'sunicast measurement and optionally MBSFN (broadcast) measurement.

FIG. 17 is a flow chart 1700 of a method of wireless communicationaccording to a second approach. The method may be performed by a UE. At1702, the UE receives, from a base station, a retransmission indicator.At 1704, the UE receives, from the base station, a broadcastretransmission of a signal corresponding to the retransmission indicatorupon reception of the retransmission indicator. At 1706, the UE combinesthe broadcast retransmission of the signal and an initial transmissionof the signal previously received by the UE to decode the signal. Forexample, as discussed supra, the eNB may send the UE an indicator of abroadcast retransmission of the signal. As discussed supra, aftertransmitting the broadcast retransmission indicator, the eNB retransmitsthe broadcast signal to the UE. As discussed supra, the UE combines thebroadcast retransmission and the initial transmission to generate thebroadcast signal, in order to improve the signal quality. As discussedsupra, the UE may combine multiple retransmissions of the signal withthe initial transmission of the signal to generate the broadcast signal.In such a case, before each of the multiple retransmissions of thesignal, the eNB may send a broadcast retransmission indicatorcorresponding to each of the multiple retransmissions of the signal tothe UE.

In an aspect, the broadcast retransmission is performed in the same MSPas the initial transmission of the signal or a different MSP from theinitial transmission of the signal. As discussed supra, the eNB mayretransmit the broadcast signal in the same MSP as an MSP of aninitially transmitted eMBMS signal or in a different MSP.

FIG. 18A is a flow chart 1800 of a method of wireless communicationexpanding from FIG. 17. The method may be performed by a UE. At 1802,the UE receives from the base station information associated with acommon NACK resource. At 1804, the UE transmits a NACK via the commonNACK resource to the base station when the UE fails to decode thesignal. In an aspect, the common NACK resource is shared by a group ofUEs including the UE. In an aspect, the UE receives the broadcastretransmission of the signal from the base station based on adetermination by the MCE to retransmit the signal based on an energymetric of the transmitted NACK. For example, as discussed supra, an eNBmay send information on a common NACK resource to each of the UEs in thesame group. As discussed supra, when the UE fails to decode packets ofthe signal of the initial transmission, the UE sends a NACK to the eNBvia the common NACK resource. As discussed supra, based on the energymetric of the NACK, the MCE decides whether to prompt the eNB tore-transmit the packets of the signal to the UE. As discussed supra, thecommon NACK resource is assigned for the UEs in the same group and isshared by the UEs in the same group.

In an aspect, the information on the NACK resource is received at the UEvia a SIB13, a MCCH, dedicated signaling, or any combination thereof. Inan aspect, broadcast retransmission of the signal is received in one ormore packets of a next MSP. In an aspect, the UE receives theretransmission indicator in the MSI before the at least one broadcastretransmission to differentiate an initial transmission and the at leastone broadcast retransmission.

FIG. 18B is a flow chart 1850 of a method of wireless communicationexpanding from FIG. 17. The method may be performed by a UE. At 1852,the UE receives information associated with a common NACK resource and aG-RNTI from the base station. At 1854, the UE transmits a NACK via thecommon NACK resource from the UE when the UE fails to decode the signal.In an aspect, the common NACK resource is shared by a group of UEsincluding the UE. In an aspect, the UE receives the broadcastretransmission of the signal based on scheduling on the G-RNTI and theretransmission indicator. For example, as discussed supra, an eNB sendsthe configured NACK resource and a G-RNTI to the UE. As discussed supra,when the UE fails to decode packets of the signal, the UE sends a NACKto an eNB via the configured NACK resource. As discussed supra, if theeNB determines to retransmit the signal, the eNB sends a retransmissionindicator to the UE. Subsequently, as discussed supra, the eNB schedulesa transmission addressed by G-RNTI for the retransmission of the signal,and then performs the retransmission of the signal to the UE based onscheduling on the G-RNTI. As discussed supra, the common NACK resourceis assigned for the UEs in the same group and is shared by the UEs inthe same group.

In an aspect, the at least one broadcast retransmission is scheduledaccording to the G-RNTI if the base station determines to retransmit. Inan aspect, the NACK resource and the G-RNTI are configured per cell orper group per cell. In an aspect, the information on the NACK resourceis received at the UE via a SIB 13, an MCCH, dedicated signaling, or anycombination thereof.

FIG. 19 is a flow chart 1900 of a method of wireless communicationaccording to a second approach. The method may be performed by a basestation. At 1902, the base station sends an initial transmission of asignal to a UE. At 1904, the base station sends at least oneretransmission indicator to the UE. At 1906, the base station sends atleast one broadcast retransmission of the signal respectivelycorresponding to the at least one retransmission indicator to the UEafter sending the at least one retransmission indicator to facilitatedecoding of the signal based on a combination of the at least onebroadcast retransmission of the signal and the initial transmission ofthe signal. For example, as discussed supra, after the eNB initiallytransmits a broadcast signal (e.g., an eMBMS signal), the eNB may sendthe UE an indicator of a broadcast retransmission of the signal. Asdiscussed supra, after transmitting the broadcast retransmissionindicator, the eNB retransmits the broadcast signal to the UE, such thatUE may combine the broadcast retransmission and the initial transmissionto generate the broadcast signal.

In an aspect, the at least one broadcast retransmission is performedusing the same multicast channel scheduling period (MSP) as an MSP ofthe initial transmission of the signal or using a different MSP from theMSP of the initial transmission of the signal.

In an aspect, the base station is prompted by an MCE to send the atleast one broadcast retransmission of the signal to the UE one or moretimes based on signal quality of a single site MBSFN area and an MCS. Inan aspect, the base station is prompted to send the at least onebroadcast retransmission of the signal when an SNR of the single siteMBSFN area is less than or equal to an SNR threshold. For example, asdiscussed supra, based on a signal quality (e.g., an SNR) of the MBSFNarea and an MCS, an MCE informs eNBs to repeat transmission(retransmission) of each packet one or more times. As discussed supra,for example, if the SNR is low (e.g., below a certain threshold), thenthe MCE may inform the eNBs to retransmit the signal one or more times.

FIG. 20A is a flow chart 2000 of a method of wireless communicationexpanding from FIG. 17. The method may be performed by a base station.At 2002, the base station transmits information on a common NACKresource to the UE. At 2004, the base station receives an NACK via thecommon NACK resource from the UE when the UE fails to decode the signal.In an aspect, the common NACK resource is shared by a group of UEsincluding the UE, the group of UEs being served by one or more basestations including the base station. In an aspect, the base stationsends the at least one broadcast retransmission of the signal to the UEbased on a determination by the MCE to retransmit the signal based on anenergy metric of the NACK received at the one or more base stations. Forexample, as discussed supra, an eNB may send information on the commonNACK resource to each of the UEs in the same group. As discussed supra,when a UE fails to decode packets of the signal of the initialtransmission, the UE sends a NACK to the eNB via the common NACKresource. As discussed supra, based on the energy metric of the NACK,the MCE decides whether to prompt the eNB to re-transmit the packets ofthe signal to the UE. As discussed supra, the common NACK resource isassigned for the UEs in the same group and is shared by the UEs in thesame group

In an aspect, the information on the NACK resource is transmitted to theUE via a SIB13, an MCCH, dedicated signaling, or any combinationthereof. In an aspect, the at least one broadcast retransmission is sentin one or more packets of a next MSP.

FIG. 20B is a flow chart 2050 of a method of wireless communicationexpanding from FIG. 17. The method may be performed by a base station.At 2052, the base station transmits information on a common NACKresource and a G-RNTI to a UE. At 2054, the base station receives anNACK via the common NACK resource from the UE when the UE fails todecode the signal. In an aspect, the common NACK resource is shared by agroup of UEs including the UE, the group of UEs being served by one ormore base stations including the base station. In an aspect, the basestation sends the at least one broadcast retransmission of the signal tothe UE based on an energy metric of the received NACK and scheduling onthe G-RNTI. As discussed supra, for example, an eNB sends the configuredNACK resource and a G-RNTI to the UE. As discussed supra, when the UEfails to decode packets of the signal, the UE sends a NACK to an eNB viathe configured NACK resource. As discussed supra, the common NACKresource is assigned for the UEs in the same group and is shared by theUEs in the same group

In an aspect, the at least one broadcast retransmission is scheduledaccording to the G-RNTI if the base station determines to retransmit. Inan aspect, the NACK resource and the G-RNTI are configured per cell orper group per cell. In an aspect, the information on the NACK resourceis transmitted to the UE via a SIB 13, an MCCH, dedicated signaling, orany combination thereof.

FIG. 21 is a flow chart 2100 of a method of wireless communicationaccording to a third approach. The method may be performed by a UE. At2102, the UE receives a serving cell MBMS signal from a serving cell ofthe UE and at least one neighbor cell MBMS signal from at least oneneighbor cell. For example, referring back to FIG. 11, for a UE 1152 inthe MBSFN cell 1102, the serving cell is the MBSFN cell 1102 a, andneighbor cells are MBSFN cells 1112 b and 1112 c. The UE 1152 receivessignals from the serving cell and the neighbor cells.

At 2104, the UE determines a degree of synchronization between theserving cell MBMS signal and the neighbor cell MBMS signal. At 2106, theUE determines whether the degree of synchronization is greater than orequal to a threshold. If the degree of synchronization is greater thanor equal to the threshold, at 2108, the UE buffers a timing differencebetween the serving cell and the at least one neighbor cell upon adetermination that the degree of synchronization is greater than orequal to a threshold, and subsequently combines at 2112 the serving cellMBMS signal and the neighbor cell MBMS signal based on the degree ofsynchronization. In an aspect, the combining is based on the timingdifference. In an aspect, the buffering the timing difference mayinclude buffering one or more LLRs for the timing difference. Forexample, as discussed supra, if the UE determines that the degree ofsynchronization of the serving cell signal and a neighbor cell signal isgreater than or equal to a threshold, the UE determines that the servingcell and the neighbor cell are at least loosely synchronized. In such acase, as discussed supra, the UE buffers a timing difference between aserving cell MBMS signal and an neighbor cell MBMS signal to combine thesignals based on the timing difference.

If the degree of synchronization is less than the threshold, at 2110,the UE buffers a subframe as a whole upon determining that the degree ofsynchronization is less than a threshold, and subsequently combines at2112 the serving cell MBMS signal and the neighbor cell MBMS signalbased on the degree of synchronization. In an aspect, the combining isbased on the buffered subframe. For example, as discussed supra, if theUE determines that the degree of synchronization of the serving cellsignal and a neighbor cell signal is less than a threshold, the UEdetermines that the serving cell and the neighbor cell are asynchronous.In such a case, as discussed supra, the UE buffers the entire subframeof each signal, and then combines the signals.

FIG. 22 is a conceptual data flow diagram 2200 illustrating the dataflow between different modules/means/components in an exemplaryapparatus 2202. The apparatus 2202 may be a UE. The apparatus includes areceiving module 2204, a transmission module 2206, a UC/BC managementmodule 2208, a parameter management module 2210, a decoding module 2212,a NACK management module 2214, and a synchronization module 2216.

According to a first approach, the UC/BC management module 2208determines via the parameter management module 2210 through 2252 whetherthe apparatus 2202 is located within a sub-region of an MBSFN area basedon one or more parameters. The UC/BC management module 2208 receives viathe receiving module 2204 through 2254 based on the determination by theUC/BC management module 2208 a service over broadcast when the UE islocated within the sub-region of the MBSFN area or over unicast when theUE is not located within the sub-region. In an aspect, the MBSFN area issmaller than a unicast area. In an aspect, the one or more parametersmay include a characteristic associated with a broadcast service, acharacteristic associated with a unicast service, a timing advancevalue, a location of the apparatus 2202, a path loss value, a parameterof the sub-region of the MBSFN area, a geometry, or any combinationthereof.

In one aspect, when the apparatus 2202 initially receives the serviceover broadcast, the UC/BC management module 2208 may switch fromreception of the service over broadcast to reception of the service overunicast based on the one or more parameters. In one aspect, when theapparatus 2202 initially receives the service over broadcast, the UC/BCmanagement module 2208 may receive via the receiving module 2204 through2254, from a base station 2250, one or more thresholds associated withthe one or more parameters, and switch from receiving the service overbroadcast to receiving the service over unicast based on the one or morethresholds and the one or more parameters through 2252. In one aspect,when the apparatus 2202 initially receives the service over broadcast,the UC/BC management module 2208 may receive via the receiving module2204 through 2254 a handover command from a base station 2250, where thehandover command is generated by the base station 2250 based on the oneor more parameters, and switch from reception of the service overbroadcast to reception of the service over unicast based on the handovercommand.

In one aspect, when the apparatus 2202 initially receives the serviceover unicast, the parameter management module 2210 may measure signalquality from the MBSFN area while receiving the service over unicast,and the UC/BC management module 2208 may switch from reception of theservice over unicast to reception of the service over broadcast based onthe measured signal quality through 2252. In one aspect, when theapparatus 2202 initially receives the service over unicast, the UC/BCmanagement module 2208 may receive via the receiving module 2204 through2254 one or more thresholds corresponding to the one or more parametersfrom a base station, and switch from reception of the service overunicast to reception of the service over broadcast based on the one ormore thresholds and the one or more parameters through 2252. In oneaspect, when the apparatus 2202 initially receives the service overunicast, the parameter management module 2210 performs a unicastmeasurement of the apparatus 2202, an MBSFN measurement, or anycombination thereof, and transmits via the transmission module 2206through 2256 the unicast measurement of the apparatus 2202, the MBSFNmeasurement, or any combination thereof, to the base station 2250.Subsequently, the UC/BC management module 2208 receives via thereceiving module 2204 through 2254 a command from the base station 2250to switch from reception of the service over unicast to reception of theservice over broadcast based on the unicast measurement of the apparatus2202, the MBSFN measurement, or any combination thereof, and switchesfrom reception of the service over unicast to reception of the serviceover broadcast based on the command.

According to a second approach, the decoding module 2212 receives fromthe base station 2250 via the receiving module 2204 through 2258 aretransmission indicator, and receives from the base station 2250 viathe receiving module 2204 through 2258 a broadcast retransmission of asignal corresponding to the retransmission indicator upon reception ofthe retransmission indicator. The decoding module 2212 combines thebroadcast retransmission of the signal and an initial transmission ofthe signal previously received by the apparatus 2202 to decode thesignal. In an aspect, the broadcast retransmission may be performed inthe same MSP as the initial transmission of the signal or a differentMSP from the initial transmission of the signal.

In an aspect, a NACK management module 2214 receives from the basestation 2250 via the receiving module 2204 through 2260 information on acommon NACK resource, and transmits a NACK via the common NACK resourcethrough 2262, via the transmission module 2206, to the base station 2250when the apparatus 2202 fails to decode the signal via the decodingmodule 2212. In an aspect, the common NACK resource is shared by a groupof UEs including the apparatus 2202. In an aspect, the apparatus 2202receives via the receiving module 2204 the at least one broadcastretransmission of the signal from the base station 2250 based on adetermination by the MCE to retransmit the signal based on an energymetric of the transmitted NACK.

In an aspect, the information associated with the NACK resource isreceived at the apparatus 2202 via a SIB13, an MCCH, dedicatedsignaling, or any combination thereof. In an aspect, the broadcastretransmission of the signal is received in one or more packets of nextMSP. In an aspect, the apparatus 2202 receives the retransmissionindicator in an MSI before the broadcast retransmission to differentiatethe initial transmission of the signal and the broadcast retransmission.

In an aspect, the NACK management module 2214 receives via the receivingmodule 2204 through 2260 information associated with a common NACKresource and a G-RNTI from the base station 2250. The NACK managementmodule 2214 transmits a NACK via the common NACK resource through 2262,via the transmission module 2206, from the apparatus 2202 when theapparatus 2202 fails to decode the signal. In an aspect, the common NACKresource is shared by a group of UEs including the apparatus 2202. In anaspect, the apparatus 2202 receives via the receiving module 2204 thebroadcast retransmission of the signal based on scheduling on the G-RNTIand the retransmission indicator.

In an aspect, the at least one broadcast retransmission is scheduledaccording to the G-RNTI if the base station 2250 determines toretransmit. In an aspect, the NACK resource and the G-RNTI areconfigured per cell or per group per cell. In an aspect, the informationon the NACK resource is received at the apparatus 2202 via a SIB 13, anMCCH, dedicated signaling, or any combination thereof.

According to a third approach, the synchronization module 2216 receivesvia the receiving module 2204 through 2264 a serving cell MBMS signalfrom a serving cell of the apparatus 2202 and a neighbor cell MBMSsignal from a neighbor cell, and determines a degree of synchronizationbetween the serving cell MBMS signal and the neighbor cell MBMS signal.The decoding module 2212 combines the serving cell MBMS signal and theneighbor cell MBMS signal based on the degree of synchronization through2266.

In an aspect, the synchronization module 2216 buffers a timingdifference between the serving cell and the neighbor cell upon adetermination that the degree of synchronization is greater than orequal to a threshold. In an aspect, the combining by the decoding module2212 is based on the timing difference. In an aspect, the buffering thetiming difference may include buffering one or more LLRs for the timingdifference.

In an aspect, the synchronization module 2216 buffers a subframe as awhole upon a determination that the degree of synchronization is lessthan a threshold. In an aspect, the combining by the decoding module2212 is based on the buffered subframe.

The apparatus may include additional modules that perform each of thesteps of the algorithm in the aforementioned flow charts of FIGS. 12-14,17, 18, and 21. As such, each step in the aforementioned flow charts ofFIGS. 12-14, 17, 18, and 21 may be performed by a module and theapparatus may include one or more of those modules. The modules may beone or more hardware components specifically configured to carry out thestated processes/algorithm, implemented by a processor configured toperform the stated processes/algorithm, stored within acomputer-readable medium for implementation by a processor, or somecombination thereof.

FIG. 23 is a diagram 2300 illustrating an example of a hardwareimplementation for an apparatus 2202′ employing a processing system2314. The processing system 2314 may be implemented with a busarchitecture, represented generally by the bus 2324. The bus 2324 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 2314 and the overalldesign constraints. The bus 2324 links together various circuitsincluding one or more processors and/or hardware modules, represented bythe processor 2304, the modules 2204, 2206, 2208, 2210, 2212, 2214,2216, and the computer-readable medium/memory 2306. The bus 2324 mayalso link various other circuits such as timing sources, peripherals,voltage regulators, and power management circuits, which are well knownin the art, and therefore, will not be described any further.

The processing system 2314 may be coupled to a transceiver 2310. Thetransceiver 2310 is coupled to one or more antennas 2320. Thetransceiver 2310 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 2310 receives asignal from the one or more antennas 2320, extracts information from thereceived signal, and provides the extracted information to theprocessing system 2314, specifically the receiving module 2204. Inaddition, the transceiver 2310 receives information from the processingsystem 2314, specifically the transmission module 2206, and based on thereceived information, generates a signal to be applied to the one ormore antennas 2320. The processing system 2314 includes a processor 2304coupled to a computer-readable medium/memory 2306. The processor 2304 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 2306. The software, whenexecuted by the processor 2304, causes the processing system 2314 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 2306 may also be used forstoring data that is manipulated by the processor 2304 when executingsoftware. The processing system further includes at least one of themodules 2204, 2206, 2208, 2210, 2212, 2214, 2216, or any combinationthereof. The modules may be software modules running in the processor2304, resident/stored in the computer readable medium/memory 2306, oneor more hardware modules coupled to the processor 2304, or somecombination thereof. The processing system 2314 may be a component ofthe UE 650 and may include the memory 660 and/or at least one of the TXprocessor 668, the RX processor 656, the controller/processor 659, orany combination thereof.

In one configuration, the apparatus 2202/2202′ for wirelesscommunication includes means for determining whether the apparatus2202/2202′ is located within a sub-region of an MBSFN area based on oneor more parameters, and means for receiving, based on the determination,a service over broadcast when the apparatus 2202/2202′ is located withinthe sub-region of the MBSFN area or over unicast when the apparatus2202/2202′ is not located within the sub-region. In an aspect, the MBSFNarea is smaller than a unicast area. The apparatus 2202/2202′ may be aUE.

In an aspect, the apparatus 2202/2202′ receives the service overbroadcast and the apparatus 2202/2202′ further includes means forswitching from reception of the service over broadcast to reception ofthe service over unicast based on the one or more parameters. In anaspect, the apparatus 2202/2202′ further includes means for receiving,from a base station, one or more thresholds associated with the one ormore parameters, and means for switching between reception of theservice over broadcast and reception of the service over unicast basedon the one or more thresholds and the one or more parameters. In anaspect, the apparatus 2202/2202′ receives the service over broadcast andthe apparatus 2202/2202′ further includes means for receiving a handovercommand from a base station, where the handover command is generated bythe base station based on the one or more parameters, and means forswitching from reception of the service over broadcast to reception ofthe service over unicast based on the handover command.

In an aspect, the apparatus 2202/2202′ receives the service over unicastand the apparatus 2202/2202′ further includes means for measuring signalquality from the MBSFN area, and means for switching from reception ofthe service over unicast to reception of the service over broadcastbased on the measured signal quality. In an aspect, the apparatus2202/2202′ receives the service over unicast and the apparatus2202/2202′ further includes means for performing a unicast measurementof the apparatus 2202/2202′, an MBSFN measurement, or any combinationthereof, means for transmitting the unicast measurement of the apparatus2202/2202′, the MBSFN measurement, or any combination thereof, to a basestation, means for receiving a command from the base station to switchfrom reception the service over unicast to receiving the service overbroadcast based on the transmission, and means for switching fromreception of the service over unicast to reception of the service overbroadcast based on the command.

In another configuration, the apparatus 2202/2202′ for wirelesscommunication includes means for receiving from a base station aretransmission indicator, means for receiving from the base station abroadcast retransmission of a signal corresponding to the retransmissionindicator upon reception of the retransmission indicator, and means forcombining the broadcast retransmission of the signal and an initialtransmission of the signal previously received by the apparatus2202/2202′ to decode the signal. The apparatus 2202/2202′ may be a UE.The apparatus 2202/2202′ may further include means for receiving fromthe base station information associated with a common NACK resource, andmeans for transmitting a NACK via the common NACK resource to the basestation when the apparatus 2202/2202′ fails to decode the signal. In anaspect, the common NACK resource is shared by a group of UEs includingthe apparatus 2202/2202′. In an aspect, the apparatus 2202/2202′receives the broadcast retransmission of the signal from the basestation based on a determination by the MCE to retransmit the signalbased on an energy metric of the transmitted NACK. The apparatus2202/2202′ may further include means for receiving informationassociated with a common NACK resource and a G-RNTI from the basestation, and means for transmitting a NACK via the common NACK resourcefrom the apparatus 2202/2202′ when the apparatus 2202/2202′ fails todecode the signal. In an aspect, the common NACK resource is shared by agroup of UEs including the apparatus 2202/2202′. In an aspect, theapparatus 2202/2202′ receives the broadcast retransmission of the signalbased on scheduling on the G-RNTI and the retransmission indicator.

In another configuration, the apparatus 2202/2202′ for wirelesscommunication includes means for receiving a serving cell MBMS signalfrom a serving cell of the apparatus 2202/2202′ and a neighbor cell MBMSsignal from a neighbor cell, means for determining a degree ofsynchronization between the serving cell MBMS signal and the at leastone neighbor cell MBMS signal, and means for combining the serving cellMBMS signal and the at least one neighbor cell MBMS signal based on thedegree of synchronization. The apparatus 2202/2202′ may be a UE. Theapparatus 2202/2202′ may further include means for buffering a timingdifference between the serving cell and the neighbor cell upon adetermination that the degree of synchronization is greater than orequal to a threshold. In an aspect, the combining is based on the timingdifference. The apparatus 2202/2202′ may further include means forbuffering a subframe as a whole upon a determination that the degree ofsynchronization is less than a threshold. In an aspect, the combining isbased on the buffered subframe.

The aforementioned means may be one or more of the aforementionedmodules of the apparatus 2202 and/or the processing system 2314 of theapparatus 2202′ configured to perform the functions recited by theaforementioned means. As described supra, the processing system 2314 mayinclude the TX Processor 668, the RX Processor 656, and thecontroller/processor 659. As such, in one configuration, theaforementioned means may be the TX Processor 668, the RX Processor 656,and the controller/processor 659 configured to perform the functionsrecited by the aforementioned means.

FIG. 24 is a conceptual data flow diagram 2400 illustrating the dataflow between different modules/means/components in an exemplaryapparatus 2402. The apparatus 2402 may be an eNB. The apparatus includesa receiving module 2404, a transmission module 2406, a servicemanagement module 2408, a parameter management module 2410, aretransmission management module 2412, and a NACK management module2414.

According to a first approach, the service management module 2408provides via the transmission module 2406 through 2452 a service overbroadcast to a UE 2450 in a sub-region of an MBSFN area, and theparameter management module 2410 sends via the transmission module 2416through 2454 a signal associated with one or more parameters to the UE2450, the signal causing the UE 2450 to switch from receiving theservice over broadcast to receiving the service over unicast. In anaspect, the MBSFN area is smaller than a unicast area. In an aspect, theone or more parameters may include a characteristic associated with abroadcast service, a characteristic associated with a unicast service, atiming advance value, a location of the UE 2450, a path loss value, aparameter of the sub-region of the MBSFN area, and a geometry.

In an aspect, the signal includes one or more thresholds for the one ormore parameters, the one or more thresholds for the one or moreparameters causing the UE 2450 to switch from receiving the service overbroadcast to receiving the service over unicast. In an aspect, theapparatus 2402 determines to send a handover command via thetransmission module 2406 in the signal to the UE 2450 based on the oneor more parameters, and the handover command causes the UE 2450 toswitch from receiving the service over broadcast to receiving theservice over unicast.

According to another aspect of the first approach, the servicemanagement module 2408 provides via the transmission module 2406 through2452 a service over unicast to the UE 2450, and the parameter managementmodule 2410 sends via the transmission module 2416 through 2454 a signalassociated with one or more parameters to the UE, the signal causing theUE to switch from receiving the service over unicast to receiving theservice over broadcast in a sub-region of a MBSFN area. In an aspect,the MBSFN area is smaller than a unicast area. In an aspect, the one ormore parameters may include a characteristic associated with a broadcastservice, a characteristic associated with a unicast service, a timingadvance value, a location of the UE 2450, a path loss value, a parameterof the sub-region of the MBSFN area, and a geometry.

In an aspect, the signal includes one or more thresholds for the one ormore parameters, the one or more thresholds for the one or moreparameters causing the UE 2450 to switch from receiving the service overunicast to receiving the service over broadcast. In an aspect, theapparatus 2402 determines to send a command via the transmission module2406 in the signal to the UE 2450 based on the one or more parameters,and the command causes the UE 2450 to switch from receiving the serviceover unicast to receiving the service over broadcast, the command beingbased on a unicast measurement of the UE 2450, an MBSFN measurementreceived via the receiving module 2404, or any combination thereof,through 2456.

According to a second approach, the transmission module 2406 sends aninitial transmission of a signal the UE 2450. The retransmissionmanagement module 2412 sends via the transmission module 2406 through2458 at least one retransmission indicator to the UE 2450, and sends viathe transmission module 2406 through 2458 at least one broadcastretransmission of the signal respectively corresponding to the at leastone retransmission indicator to the UE 2450 after sending the at leastone retransmission indicator to facilitate decoding of the signal basedon a combination of the at least one broadcast retransmission of thesignal and the initial transmission of the signal.

In an aspect, the at least one broadcast retransmission may be performedusing the same MSP as an MSP of the initial transmission of the signalor using a different MSP from the MSP of the initial transmission of thesignal.

In an aspect, the apparatus 2402 is prompted by an MCE via the receivingmodule 2404 and the retransmission management module 2412 through 2460to send the at least one broadcast retransmission of the signal to theUE 2450 one or more times based on signal quality of a single site MBSFNarea and an MCS. In an aspect, the apparatus 2402 may be prompted tosend the at least one broadcast retransmission of the signal when a SNRof the single site MBSFN area is less than or equal to an SNR threshold.

In an aspect, a NACK management module 2414 transmits via thetransmission module 2406 through 2462 information on a common NACKresource to the UE 2450, and receives a NACK via the common NACKresource, via the receiving module 2404 through 2464, from the UE 2450when the UE 2450 fails to decode the signal. In an aspect, the commonNACK resource is shared by a group of UEs including the UE 2450, thegroup of UEs being served by one or more base stations including theapparatus 2402. In an aspect, the apparatus 2402 sends the at least onebroadcast retransmission of the signal to the UE 2450 based on adetermination by the MCE to retransmit the signal based on an energymetric of the NACK received at the one or more base stations includingthe apparatus 2402.

In an aspect, the information on the NACK resource is transmitted to theUE 2450 via a SIB13, a MCCH, dedicated signaling, or any combinationthereof, via the transmission module 2406 through 2462. In an aspect,the at least one broadcast retransmission is sent in one or more packetsof a next MSP. In an aspect, the apparatus 2402 transmits an indicatorin an MSI before the at least one broadcast retransmission to the UE2450 to differentiate an initial transmission and the at least onebroadcast retransmission.

In an aspect, a NACK management module 2414 transmits via thetransmission module 2406 through 2462 information on a common NACKresource and a G-RNTI to the UE 2450, and receives a NACK via the commonNACK resource, via the receiving module 2404, from the UE 2450 when theUE 2450 fails to decode the signal. In an aspect, the common NACKresource is shared by a group of UEs including the UE 2450, the group ofUEs being served by one or more base stations including the apparatus2402. In an aspect, the apparatus 2402 sends the at least one broadcastretransmission of the signal to the UE 2450 based on an energy metric ofthe received NACK and scheduling on the G-RNTI.

In an aspect, the at least one broadcast retransmission is scheduledaccording to the G-RNTI if the apparatus 2402 determines to retransmit.In an aspect, the NACK resource and the G-RNTI are configured per cellor per group per cell. In an aspect, the information on the NACKresource is transmitted to the UE 2450 via a SIB 13, an MCCH, dedicatedsignaling, or any combination thereof.

The apparatus may include additional modules that perform each of thesteps of the algorithm in the aforementioned flow charts of FIGS. 15,16, 19, 20A, and 20B. As such, each step in the aforementioned flowcharts of FIGS. 15, 16, 19, 20A, and 20B may be performed by a moduleand the apparatus may include one or more of those modules. The modulesmay be one or more hardware components specifically configured to carryout the stated processes/algorithm, implemented by a processorconfigured to perform the stated processes/algorithm, stored within acomputer-readable medium for implementation by a processor, or somecombination thereof.

FIG. 25 is a diagram 2500 illustrating an example of a hardwareimplementation for an apparatus 2402′ employing a processing system2514. The processing system 2514 may be implemented with a busarchitecture, represented generally by the bus 2524. The bus 2524 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 2514 and the overalldesign constraints. The bus 2524 links together various circuitsincluding one or more processors and/or hardware modules, represented bythe processor 2504, the modules 2404, 2406, 2408, 2410, 2412, 2414, andthe computer-readable medium/memory 2506. The bus 2524 may also linkvarious other circuits such as timing sources, peripherals, voltageregulators, and power management circuits, which are well known in theart, and therefore, will not be described any further.

The processing system 2514 may be coupled to a transceiver 2510. Thetransceiver 2510 is coupled to one or more antennas 2520. Thetransceiver 2510 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 2510 receives asignal from the one or more antennas 2520, extracts information from thereceived signal, and provides the extracted information to theprocessing system 2514, specifically the receiving module 2404. Inaddition, the transceiver 2510 receives information from the processingsystem 2514, specifically the transmission module 2406, and based on thereceived information, generates a signal to be applied to the one ormore antennas 2520. The processing system 2514 includes a processor 2504coupled to a computer-readable medium/memory 2506. The processor 2504 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 2506. The software, whenexecuted by the processor 2504, causes the processing system 2514 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 2506 may also be used forstoring data that is manipulated by the processor 2504 when executingsoftware. The processing system further includes at least one of themodules 2404, 2406, 2408, 2410, 2412, 2414, or any combination thereof.The modules may be software modules running in the processor 2504,resident/stored in the computer readable medium/memory 2506, one or morehardware modules coupled to the processor 2504, or some combinationthereof. The processing system 2514 may be a component of the eNB 610and may include the memory 676 and/or at least one of the TX processor616, the RX processor 670, the controller/processor 675, or anycombination thereof.

In one configuration, the apparatus 2402/2402′ for wirelesscommunication includes means for providing a service over broadcast to aUE in a sub-region of an MBSFN area, and means for sending a signalassociated with one or more parameters to the UE, the signal causing theUE to switch from receiving the service over broadcast to receiving theservice over unicast. In an aspect, the MBSFN area is smaller than aunicast area. The apparatus 2402/2402′ may be a base station. In oneconfiguration, the apparatus 2402/2402′ for wireless communicationincludes means for providing a service over unicast to a UE, and meansfor sending a signal associated with one or more parameters to the UE,the signal causing the UE to switch from receiving the service overunicast to receiving the service over broadcast in a sub-region of anMBSFN area. In an aspect, the MBSFN area is smaller than a unicast area.

In one configuration, the apparatus 2402/2402′ for wirelesscommunication includes means for sending an initial transmission of asignal to a UE, means for sending at least one retransmission indicatorto the UE, and means for sending at least one broadcast retransmissionof the signal respectively corresponding to the at least oneretransmission indicator to the UE after sending the at least oneretransmission indicator to facilitate decoding of the signal based on acombination of the at least one broadcast retransmission of the signaland the initial transmission of the signal. The apparatus 2402/2402′ maybe a base station. The apparatus 2402/2402′ may further include meansfor transmitting information on a common NACK resource to the UE, andmeans for receiving a NACK via the common NACK resource from the UE whenthe UE fails to decode the signal. In an aspect, the common NACKresource is shared by a group of UEs including the UE, the group of UEsbeing served by one or more base stations including the apparatus2402/2402′. In an aspect, the apparatus 2402/2402′ sends the at leastone broadcast retransmission of the signal to the UE based on adetermination by the MCE to retransmit the signal based on an energymetric of the NACK received at the one or more base stations includingthe apparatus 2402/2402′. The apparatus 2402/2402′ may further includemeans for transmitting information on a common NACK resource and aG-RNTI to a UE, and means for receiving an NACK via the common NACKresource from the UE when the UE fails to decode the signal. In anaspect, the common NACK resource is shared by a group of UEs includingthe UE, the group of UEs being served by one or more base stationsincluding the apparatus 2402/2402′. In an aspect, the apparatus2402/2402′ sends the at least one broadcast retransmission of the signalto the UE based on an energy metric of the received NACK and schedulingon the G-RNTI.

The aforementioned means may be one or more of the aforementionedmodules of the apparatus 2402 and/or the processing system 2514 of theapparatus 2402′ configured to perform the functions recited by theaforementioned means. As described supra, the processing system 2514 mayinclude the TX Processor 616, the RX Processor 670, and thecontroller/processor 675. As such, in one configuration, theaforementioned means may be the TX Processor 616, the RX Processor 670,and the controller/processor 675 configured to perform the functionsrecited by the aforementioned means.

It is understood that the specific order or hierarchy of steps in theprocesses/flow charts disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of steps in the processes/flow charts may berearranged. Further, some steps may be combined or omitted. Theaccompanying method claims present elements of the various steps in asample order, and are not meant to be limited to the specific order orhierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects.” Unless specificallystated otherwise, the term “some” refers to one or more. Combinationssuch as “at least one of A, B, or C,” “at least one of A, B, and C,” and“at least one of A, B, C, or any combination thereof” include anycombination of A, B, and/or C, and may include multiples of A, multiplesof B, or multiples of C. Specifically, combinations such as “at leastone of A, B, or C,” “at least one of A, B, and C,” and “at least one ofA, B, C, or any combination thereof” may be A only, B only, C only, Aand B, A and C, B and C, or A and B and C, where any such combinationsmay contain one or more member or members of A, B, or C. All structuraland functional equivalents to the elements of the various aspectsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. No claim element is to be construed as a means plus functionunless the element is expressly recited using the phrase “means for.”

What is claimed is:
 1. A method of wireless communication by a userequipment (UE), comprising: determining whether the UE is located withina sub-region of a multicast broadcast single-frequency network (MBSFN)area based on one or more parameters; and receiving, based on thedetermination, a service over broadcast when the UE is located withinthe sub-region of the MBSFN area or over unicast when the UE is notlocated within the sub-region, wherein the MBSFN area is smaller than aunicast area.
 2. The method of claim 1, wherein the one or moreparameters comprise: a characteristic associated with a broadcastservice, a characteristic associated with a unicast service, a timingadvance value, a location of the UE, a path loss value, a parameter ofthe sub-region of the MBSFN area, a geometry, or a combination thereof.3. The method of claim 1, wherein the UE receives the service overbroadcast and the method further comprises: switching from reception ofthe service over broadcast to reception of the service over unicastbased on the one or more parameters.
 4. The method of claim 1, furthercomprising: receiving, from a base station, one or more thresholdsassociated with the one or more parameters; and switching betweenreception of the service over broadcast and reception of the serviceover unicast based on the one or more thresholds and the one or moreparameters.
 5. The method of claim 1, wherein the UE receives theservice over broadcast and the method further comprises: receiving ahandover command from a base station, wherein the handover command isgenerated by the base station based on the one or more parameters; andswitching from reception of the service over broadcast to reception ofthe service over unicast based on the handover command.
 6. The method ofclaim 1, wherein the UE receives the service over unicast and the methodfurther comprises: measuring signal quality from the MBSFN area; andswitching from reception of the service over unicast to reception of theservice over broadcast based on the measured signal quality.
 7. Themethod of claim 1, wherein the UE receives the service over unicast andthe method further comprises: performing a unicast measurement of theUE, an MBSFN measurement, or a combination thereof; transmitting theunicast measurement of the UE, the MBSFN measurement, or a combinationthereof, to a base station; receiving a command from the base station toswitch from reception of the service over unicast to reception of theservice over broadcast based the transmission; and switching fromreception of the service over unicast to reception of the service overbroadcast based on the command.
 8. A method of wireless communication bya user equipment (UE), comprising: receiving, from a base station, aretransmission indicator; receiving, from the base station, a broadcastretransmission of a signal corresponding to the retransmission indicatorupon reception of the retransmission indicator; and combining thebroadcast retransmission of the signal and an initial transmission ofthe signal previously received by the UE to decode the signal.
 9. Themethod of claim 8, wherein the broadcast retransmission is performed inthe same multicast channel scheduling period (MSP) as the initialtransmission of the signal or a different MSP from the initialtransmission of the signal.
 10. The method of claim 8, furthercomprising: receiving, from the base station, information associatedwith a common negative acknowledgement (NACK) resource; and transmittinga NACK via the common NACK resource to the base station when the UEfails to decode the signal, wherein the common NACK resource is sharedby a group of UEs including the UE, wherein the UE receives thebroadcast retransmission of the signal from the base station based on adetermination by a multicast coordination entity (MCE) to retransmit thesignal based on an energy metric of the transmitted NACK.
 11. The methodof claim 10, wherein the information associated with the NACK resourceis received at the UE via a system information block 13 (SIB 13), amulticast control channel (MCCH), dedicated signaling, or a combinationthere of.
 12. The method of claim 10, wherein the broadcastretransmission of the signal is received in one or more packets of anext MSP.
 13. The method of claim 10, wherein the UE receives theretransmission indicator in a multicast channel scheduling information(MSI) before the broadcast retransmission to differentiate an initialtransmission of the signal and the broadcast retransmission.
 14. Themethod of claim 8, further comprising: receiving information associatedwith a common NACK resource and a group radio network temporaryidentifier (G-RNTI) from the base station; and transmitting a NACK viathe common NACK resource from the UE when the UE fails to decode thesignal, wherein the common NACK resource is shared by a group of UEsincluding the UE, wherein the UE receives the broadcast retransmissionof the signal based on scheduling on the G-RNTI and the retransmissionindicator.
 15. A user equipment (UE) for wireless communication,comprising: a memory; and at least one processor coupled to the memoryand configured to: determine whether the UE is located within asub-region of a multicast broadcast single-frequency network (MBSFN)area based on one or more parameters; and receive, based on thedetermination, a service over broadcast when the UE is located withinthe sub-region of the MBSFN area or over unicast when the UE is notlocated within the sub-region, wherein the MBSFN area is smaller than aunicast area.
 16. The UE of claim 15, wherein the one or moreparameters: a characteristic associated with a broadcast service, acharacteristic associated with a unicast service, a timing advancevalue, a location of the UE, a path loss value, a parameter of thesub-region of the MBSFN area, a geometry, or a combination thereof. 17.The UE of claim 15, wherein the UE receives the service over broadcastand the at least one processor is further configured to: switch fromreception of the service over broadcast to reception of the service overunicast based on the one or more parameters.
 18. The UE of claim 15,wherein the at least one processor is further configured to: receive,from a base station, one or more thresholds associated with the one ormore parameters; and switch between reception of the service overbroadcast and reception of the service over unicast based on the one ormore thresholds and the one or more parameters.
 19. The UE of claim 15,wherein the UE receives the service over broadcast and the methodfurther comprises: receiving a handover command from a base station,wherein the handover command is generated by the base station based onthe one or more parameters; and switching from reception of the serviceover broadcast to reception of the service over unicast based on thehandover command.
 20. The UE of claim 15, wherein the UE receives theservice over unicast and the at least one processor is furtherconfigured to: measure signal quality from the MBSFN area; and switchfrom reception of the service over unicast to reception of the serviceover broadcast based on the measured signal quality.
 21. The UE of claim15, wherein the UE receives the service over unicast and the at leastone processor is further configured to: perform a unicast measurement ofthe UE, an MBSFN measurement, or a combination there of; transmit theunicast measurement of the UE, the MBSFN measurement, or a combinationthereof, to a base station; receive a command from the base station toswitch from reception of the service over unicast to reception of theservice over broadcast based on the transmission; and switch fromreception of the service over unicast to reception of the service overbroadcast based on the command.
 22. A user equipment (UE) for wirelesscommunication, comprising: a memory; and at least one processor coupledto the memory and configured to: receive, from a base station, aretransmission indicator; receive, from the base station, a broadcastretransmission of a signal corresponding to the retransmission indicatorupon reception of the retransmission indicator; and combine thebroadcast retransmission of the signal and an initial transmission ofthe signal previously received by the UE to decode the signal.
 23. TheUE of claim 22, wherein the broadcast retransmission is performed in thesame multicast channel scheduling period (MSP) as the initialtransmission of the signal or a different MSP from the initialtransmission of the signal.
 24. The UE of claim 22, wherein the at leastone processor is further configured to: receive, from the base station,information associated with a common negative acknowledgement (NACK)resource; and transmit a NACK via the common NACK resource to the basestation when the UE fails to decode the signal, wherein the common NACKresource is shared by a group of UEs including the UE, wherein the UEreceives the broadcast retransmission of the signal from the basestation based on a determination by a multicast coordination entity(MCE) to retransmit the signal based on an energy metric of thetransmitted NACK.
 25. The UE of claim 24, wherein the informationassociated with the NACK resource is received at the UE via a systeminformation block 13 (SIB 13), a multicast control channel (MCCH),dedicated signaling, or a combination there of.
 26. The UE of claim 24,wherein the broadcast retransmission of the signal is received in one ormore packets of a next MSP.
 27. The UE of claim 24, wherein the UEreceives the retransmission indicator in a multicast channel schedulinginformation (MSI) before the broadcast retransmission to differentiatean initial transmission of the signal and the broadcast retransmission.28. The UE of claim 22, wherein the at least one processor is furtherconfigured to: receive information associated with a common NACKresource and a group radio network temporary identifier (G-RNTI) fromthe base station; and transmit a NACK via the common NACK resource fromthe UE when the UE fails to decode the signal, wherein the common NACKresource is shared by a group of UEs including the UE, wherein the UEreceives the broadcast retransmission of the signal based on schedulingon the G-RNTI and the retransmission indicator.